Solve for x, then reread the last sentence. A lot of Math items asked for 2x, for the area, or for the other variable. The algebra can be right and the bubble still wrong. Order of attack is in Math question order.
What did they actually ask
Circle or underline the target before you start. If you already have x, plug it back into the expression they named. Checking the value in the original setup is in plugging the answer back in.
Two-pass timing is in the two-pass method. Formulas you might have solved toward the wrong one are in ACT Math formulas.
The bottom line
Finish the algebra, then match the last sentence, not the first variable you named.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.