Mass in science is like weight. Everything is basically mass, you are mass!
First to find the missing measurement:
17-8 = 9
Perimeter = 57 (add all the sides)
Area = (7 x 8) + (9 x 16) = 200m^2
(it helps to split the shape into two parts)
X = -1 and -1.5 so the 4th answer