Here’s today’s ACT algebra question:

If x + 2y = 1, and 2x + y = 5, then x + y = ?

Let’s get to work!

A strategy to try: substitution

Rearrange the first equation to have x = 1 – 2y. Substitute that in for x in the second equation:

2(1-2y) + y = 5

2 – 4y + y = 5

-3y = 3

y = -1

Now, substitute -1 back into the first equation for y:

x + 2 (-1) = 1

x – 2 = 1

x = 3

Finally, solve the problem:

x + y = 3 + (-1) = 2

Check using the second equation:

2(3) + (-1) = 5

Work carefully and you will find that using substitution is quite easy, if a bit time-consuming! Bonus points: could you solve this arithmetic on as a system of equations instead?