Add and Subtract Rational Numbers, Challenge Answer Key

Grade 7 rational numbers: adding and subtracting positive and negative fractions, mixed numbers, and decimals. Monday practice at the challenge level.

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Lesson Notes

Pick one form for the whole problem. If fractions and decimals are mixed, either turn every decimal into a fraction or every fraction into a decimal, whichever is cleaner.

Worked example

$-3.125 - 2\tfrac{3}{4}$: eighths and quarters both turn into exact decimals, so use decimals.

$-3.125 - 2.75 = -5.875$

Use a fraction when a denominator like 3, 6, or 12 would make a decimal repeat.
Grouping symbols come first. Subtracting a group changes the sign of every term inside it.
For a story, write the expression first, then compute it.

Estimate first. Round each number to the nearest whole number to see whether your answer is close.

25 problems. Show your work in the space under each problem, then put a box around your answer. Write fraction answers as improper fractions in lowest terms. Write decimal answers as decimals. On screen, the eye at the right of each problem shows or hides the worked solution.