The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(5²) + 2π(5 x 3)
sa = 2π(25) + 2π(15)
sa = (2 x 25)π + (2 x 15)π
sa = 50π + 30π
sa = 80π

A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 12cm + 12cm + 13cm = 37cm

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 3 x 3) + (2 x 3 x 7) + (2 x 3 x 7)
sa = (18) + (42) + (42)
sa = 102

You need to find the value of c so solve the first equation in terms of x:

-2c + x = 5
x = 5 + 2c

then substitute the result (5 - -2c) into the second equation:

6c - 5(5 + 2c) = -3
6c + (-5 x 5) + (-5 x 2c) = -3
6c - 25 - 10c = -3
6c - 10c = -3 + 25
-4c = 22
c = \( \frac{22}{-4} \)
c = -5\(\frac{1}{2}\)