Simple calculation causes syntax error in Ruby - ruby-on-rails

Question

I have a simple financial app in Ruby that can keep track of a user's expenses and generate reports based on them.
Expenses belong to different categories, which affects how much of each expenses is taxes.
In my code to generate a report on expenses, I have this piece:
tax_totals = [0] * 13
totals = [0] * 13
expenses.each do |expense|
tax_ratio = tax_rate/(1+tax_rate)
category = Category.find(expense.category_id).first
tax_ratio *= category.tax_rate.to_f / 100
if !expense.rate_id.nil?
subcategory = Rate.where("id = ?", expense.rate_id).first
tax_ratio *= subcategory.tax_rate.to_f
end
tax_totals[expense.transaction_date.to_date.month] +=
(expense.amount * tax_ratio)
totals[expense.transaction_date.to_date.month] += expense.amount
end
I keep getting a syntax error on the line tax_ratio = tax_rate/(1+tax_rate):
syntax error, unexpected '(', expecting keyword_end
If I remove that line, the error moves to tax_ratio *= category.tax_rate.to_f / 100 line:
syntax error, unexpected tINTEGER, expecting keyword_end
and I have NO IDEA, where this is coming from. I don't see anything wrong with the code at all. I have very similar code in multiple functions each doing the calculations slightly differently. But only this one is an issue.
Maybe it's the lack of caffeine. Is there something wrong with this code? Could there be something else in the file causing this? How can I proceed with debugging?
Cheers!
EDIT: I figured it out. Ruby noob mistake. See answer below.

Answer 1

As written above, this is valid Ruby. I was able to get your code into a method and call it. See below:
require 'active_support/all'
require 'rspec'
class Category
def self.find(category_id)
[new]
end
def tax_rate
0.5
end
end
class Rate
def self.where(*args)
[new]
end
def tax_rate
0.5
end
end
def ratio(expenses, tax_rate)
tax_totals = [0] * 13
totals = [0] * 13
expenses.each do |expense|
tax_ratio = tax_rate/(1+tax_rate)
category = Category.find(expense.category_id).first
tax_ratio *= category.tax_rate.to_f / 100
if !expense.rate_id.nil?
subcategory = Rate.where("id = ?", expense.rate_id).first
tax_ratio *= subcategory.tax_rate.to_f
end
tax_totals[expense.transaction_date.to_date.month] +=
(expense.amount * tax_ratio)
totals[expense.transaction_date.to_date.month] += expense.amount
end
end
describe "#ratio" do
let(:expense) do
double("expense", category_id: 5, rate_id: 6, transaction_date: 5.days.ago, amount: 5)
end
let(:expenses) { [expense] }
let(:tax_rate) { 0.25 }
it "should run" do
ratio(expenses, tax_rate)
end
end

Answer 2

I am new to Ruby and Rails and to me this was the weirdest thing ever.
The error was coming from such an innocent looking line that I didn't even bother to include it in my original question.
tax_rate was a variable that was getting passed to the method. It's stored in a DB as an integer, so I needed to convert it to a decimal point. This was the more complete code:
tax_rate = tax_rate.to_f /100
tax_totals = [0] * 13
totals = [0] * 13
expenses.each do |expense|
tax_ratio = tax_rate/(1+tax_rate)
category = Category.find(expense.category_id).first
tax_ratio *= category.tax_rate.to_f / 100
if !expense.rate_id.nil?
subcategory = Rate.where("id = ?", expense.rate_id).first
tax_ratio *= subcategory.tax_rate.to_f
end
tax_totals[expense.transaction_date.to_date.month] +=
(expense.amount * tax_ratio)
totals[expense.transaction_date.to_date.month] += expense.amount
end
And that first line is what Ruby doesn't like and I still don't know why. But you can't put myVar /100 it has to be myVar / 100 or even myVar/ 100 but there absolutely needs to be a space between / and the number.