Answer:
the sum of exterior angles of a polygon is 360°
C. The product of a constant factor of six and a factor with the sum of two terms. In this case, 6 is constant, and the sum of two terms is: y+3. Since they are products, you multiple them. Therefore C would be correct.
Equation (1)

Equation (2)

Get y alone in equation (1)

Insert y in equation (2)

Let, that number = x
It would be: x * 0.65 = 52
x = 52 / 0.65
x = 80
So, that number and your answer is 80
18 is 45% of 40
45%/100 = 0.45
0.45*40=18