Answer:
x = 20
Explanation:
Formula
x1/x2 = x3/x4
Givens
x = 11
x2 = 11 + 121 = 132
x3 = 10
x4 = 10 + 5x + 10
Solution
11/132 = 10 / (5x + 10 + 10) Combine
11/132 = 10/(5x + 20) Cross multiply
11*(5x + 20) = 132 * 10 Combine on the right.
11(5x + 20 ) = 1320 Divide by 11. (You could remove the brackets, but this is easier.
11(5x + 20)/11 = 1320/11 Do the division
5x + 20 = 120 Subtract 20 from both sides
5x + 20-20 = 120 - 20 Combine
5x = 100 Divide by 5
5x/5 = 100/5
x = 20