Please expand it
(c-7d)2

c² - 14cd + 49d²

Step-by-step explanation:

Given

(c - 7d)²

= (c - 7d)(c - 7d)

Each term in the second factor is multiplied by each term in the first factor, that is

c(c - 7d) - 7d(c - 7d) ← distribute both parenthesis

= c² - 7cd - 7cd + 49d² ← collect like terms

= c² - 14cd + 49d²

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: