Answer and workings in the attachment below.
Answer:
x = 6
Step-by-step explanation:
To find the missing side, write a proportion using side lengths from each similar shape. A proportion is an equation that sets equal two ratios.

Find x by cross multiplying numerator and denominator of each fraction.
4(18) = 12x
72 = 12x
6 = x
Answer:
(x-1)(x-7)
Step-by-step explanation:
To factor the equation, find two binomials which multiply to a quadratic. The quadratic's factors are found by finding two numbers that multiply to 7 and add to -8.
-1 and -7 multiply to 7 and add to -8.
(x-1)(x-7)
M< 6 = m< 7 (vertical angles)
11x + 8 = <span>12x – 4
12x - 11x = 8 + 4
x = 12
so
m< 6 = </span>11x + 8
m< 6 = 11(12) + 8
m< 6 = 132 + 8
m< 6 = 140
m<4 = 180 - m<6
m<4 = 180 - 140
m<4 = 40
answer
<span>m<4 = 40</span>