Score report

First simplify f(x) to |-3x|, so f(5) = 15. The equation becomes 15 - f(a) = -15, which means f(a) = 30. Since |-3a| = 30, a can be 10 or -10 depending on the answer choices. The key mistake was substituting before isolating f(a).

You chose 5, but the credited answer is 10. The missed answer most likely went beyond the evidence or followed an attractive trap instead of the exact support in the text.

Absolute Value Sign Error: this trap looks reasonable because it borrows words or timing from the passage, but it does not prove the required conclusion.

Before choosing, underline the exact proof for 10 and reject any answer that adds a claim the text does not prove.

The second sentence gives a consequence, not another example. A transition such as therefore or consequently preserves the logic better than a contrast or continuation signal.

You chose A, but the credited answer is D. The missed answer most likely went beyond the evidence or followed an attractive trap instead of the exact support in the text.

Transition Logic Mismatch: this trap looks reasonable because it borrows words or timing from the passage, but it does not prove the required conclusion.

Before choosing, underline the exact proof for D and reject any answer that adds a claim the text does not prove.

The increase is 20, but percent increase is measured against the original value: 20 divided by 80 equals 25%.

You chose 20%, but the credited answer is 25%. The missed answer most likely went beyond the evidence or followed an attractive trap instead of the exact support in the text.

Percent Base Error: this trap looks reasonable because it borrows words or timing from the passage, but it does not prove the required conclusion.

Before choosing, underline the exact proof for 25% and reject any answer that adds a claim the text does not prove.