Rectangles: Area

1. D $$\eqalign{60 \div 4 &= 15 \quad \text{ side length}\\15 \times 15&=225 \text { area}}$$

2. D $$\eqalign{120 \div 4 &= 30 \quad \text{ side length}\\30 \times 30&=900 \text { area}}$$

3. D $$\eqalign{24 \div 4 &= 6 \quad \text{ side length}\\6 \times 6&=36 \text { area}}$$

4. C $$\eqalign{48 \div 4 &= 12 \quad \text{ side length}\\12 \times 12&=144 \text { area}}$$

5. B $$\eqalign{50 - (2 \times 10)&= 2x \quad \text{ perimeter minus 2 times known length = 2 times unknown length}\\50 -20&=2x\\30&=2x\\15&=x \quad\text{ width}}$$

6. C $$\eqalign{80 - (2 \times 10)&= 2x \quad \text{ perimeter minus 2 times known length = 2 times unknown length}\\80 -20&=2x\\60&=2x\\30&=x\\30\times10&=300 \quad\text{ area}}$$

7. A $$\eqalign{100 \div 10&= 10 \quad \text{ area divided by side = unknown side}\\10+10+10+10&=40  \quad\text{ All all four sides for perimeter}}$$

8. B $$\eqalign{300 \div 10&= x \quad \text{ area divided by one side = other side}\\30&=x \quad\text{ width}}$$

9. C $$\eqalign{20 \times 10 &=200 \quad\text{ area}}$$

10.  B $$\eqalign{150 \div 10&= x \quad \text{ area divided by one side = other side}\\15&=x \quad\text{ width}}$$