Respuesta :

Answer:

ST = 15

Step-by-step explanation:

Given:

QR = 3x

LM = x + 9

ST = 6x - 3

Required:

ST

Solution:

First, we need to find the value of x by creating an equation.

Based on the trapezoid mid-segment theorem, we have the following equation:

LM = ½(QR + ST)

Substitute

x + 9 = ½(3x + 6x - 3)

x + 9 = ½(9x - 3)

Multiply both sides by 2

2(x + 9) = 9x - 3

2x + 18 = 9x - 3

Collect like terms

2x - 9x = -18 - 3

-7x = -21

Divide both sides by -7

x = -21/-7

x = 3

Find ST:

ST = 6x - 3

Plug in the value of x

ST = 6(3) - 3 = 18 - 3

ST = 15