Answer:
r = 16
Step-by-step explanation:
Cross multiply:
4 x 20 = r x 5
Simplifying
4 x 20 = r x 5
Multiply 4 x 20
80 = r x 5
Reorder the terms for easier multiplication:
80 = 5r
Solve
80 = 5r
Solve for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Add '-5r' to each side of the equation.
80 + -5r = 5r + -5r
Combine like terms: 5r + -5r = 0
80 + -5r = 0
Add '-80' to each side of the equation.
80 + -80 + -5r = 0 + -80
Combine like terms: 80 + -80 = 0
0 + -5r = 0 + -80
-5r = 0 + -80
Combine like terms: 0 + -80 = -80
-5r = -80
Divide each side by '-5'.
r = 16
Simplify
r = 16
