8. By how much is the increase in the perimeter of a rectangle if the length is increased by 3 cm and the width is increased also by 2 cm?
A. 5
B. 10
C. 15
D. 20 cm
9. The area of a triangle is 8 2 and its height is 4 . What is the length of its base?
A. 2
B. 4
C. 6
D. 8
10. The area of a square and a rectangle are equal. The length of the rectangle is 9 and its width is 4 . How long is the side of the square?
A. 3
B. 6
C. 9
D. 12 ​