In this special episode of TuesdACT (and the next few episodes), we are going to work through solutions to some of the questions in *The Real ACT Prep Guide, 3rd Edition* that students are always asking about. We’re kicking it off with a math question on functions from **ACT Practice Test 5, Question 60, Page 747**!

Check out the video (above) for a full explanation and/or read the solution below!

Math Question 60 in Practice Test 5 is a classic example of an ACT question that looks pretty intimidating but is actually not that bad once you realize all you need to do is apply the same rules that you’ve learned in school and you’ll be ok. This is a pretty classic standardized test trick.

The question tells us that and asks us to find what

Let’s review functions with a simpler example.

A function is like a machine that has an input and an output. So let’s say that our function is

That’s all we need to do on problem 60 on Test 5, except now we are plugging in algebraic equations.

We need to sub in

We now have two options: We can work it out algebraically or we can plug in numbers for x and y and see which answer choice matches up.

Here’s the algebra solution:

First, FOIL the expression for a:

The entire expression then is:

The

You could also plug in numbers for

Join us next TuesdACT for another solution to a tricky problem from The *Real ACT Prep Guide*!