It's kind of not C.
Solve this proportion for 'x':
3/50 = x/2400
Hint: Cross-multiply the proportion, then do what you need to do.
It appears as if 12cm is half the length of the side so we can assume that the total length of one side is 24cm.
The area of a square is given by the equation
where s is the length of the side.

A=576
The area of this square is 576cm2.
Hope this helps!
I beleive 1 is C, and 2 is B!
Answer: x = 65.63
Explanation:
We have, 64% × x = 42 or, 64/100 × x = 42
Multiplying both sides by 100 and dividing both sides by 64, we have x = 42 × 100 64
x = 65.63
The answer to 1 is common multiple. And the answer to 2 is common denominator