The volume of a cube is height x length x width:

v = h x l x w
v = 4 x 6 x 5
v = 120

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

2a⁴ - 8a⁴ = -6a⁴

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 57° - 54° = 69°

So, d° = 54° + 69° = 123°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 57° = 123°

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

sa = 2πr² + 2πrh
sa = 2π(2²) + 2π(2 x 7)
sa = 2π(4) + 2π(14)
sa = (2 x 4)π + (2 x 14)π
sa = 8π + 28π
sa = 36π