Subtest 2
Mathematical equations
A unique integer solution in 1–20. Every letter must be right. Algebra I, done cleanly.
What you will see
Two to four letters, a handful of linear (occasionally product) equations, one solution. Letters stand for whole numbers from 1 to 20. You enter a number for each letter. The item scores only if every letter is correct.
A reliable order of attack
Look for a letter that is already isolated or sitting in a one-letter equation. Substitute. If nothing is isolated, add or subtract two equations to cancel a letter. Keep a scratch column of bounds — if a letter would have to be 0 or 21, you have an arithmetic slip. Do not bring a calculator habit; the arithmetic is small on purpose.
Common slips
Sign errors on subtraction. Forgetting that both A and B must be integers. Solving a consistent subsystem and leaving the last letter unchecked. Always plug the full tuple back into every equation before you lock the item.