Answer:
A) 2.1/6.3 = 8.7/X
Explanation:
If two rectangles are similar, the ratio of the two shorter sides should equal the ratio of the two longer sides.
The two shorter sides are 2.1 cm and 6.3 cm
The two longer sides are 8.7 cm and X.
Therefore, as ratios:
2.1 : 6.3 = 8.7 : X
⇒ 2.1/6.3 = 8.7/X