A6. By what percentage does the area of a rectangle increase or decrease if one side is extended by $20 \%$ of its length, and the other is shortened by a quarter of its length?
(A) It increases by $5 \%$.
(B) It decreases by $10 \%$.
(C) It increases by $15 \%$.
(D) It decreases by $1 \%$.
(E) The area does not change.

## II. PART
A6. The area of a rectangle with sides $1.2 a$ and $0.75 b$ is $\frac{12}{10} \frac{3}{4} \cdot a b=\frac{9}{10} \cdot a b$, so it is $10 \%$ smaller than the area of a rectangle with sides $a$ and $b$.