Answer:
Option C. 
Step-by-step explanation:
we know that
If two figures are similar, then the ratio of its corresponding sides is proportional
In this problem
Using proportion

Answer: 12 3/8
10 1/2 + 10 1/2= 21
45 3/4 - 21 = 24 3/4
24 ÷ 2 = 12
Change the 3/4 into 8ths = 6/8
Divide that in half which gives you 3/8
So the length is 12 3/8
2+1=3
15/3=5
split the 3 5's in ratio 2:1 and you get 10:5
Answer:
The diagonals of a rectangle are always congruent