Answer:
9) 15
10) 115
11) 58
12) 75
13) 23
14) 51
Explanation:
9)
The sum of the interior angles of a triangle is 180
180 -40-25 = 115
10)
The angle 155 equal the sum of 40 and x
155 - 40 = 115
11)
The angle 100 = x +42
100 - 42 = 58
12)
180 - 30 = 150
Both angles are equal to each other 150/2 = 75
13)
180 - 90 = 90
The 2 angles remaining equal 90
2x + 21 + x = 90 Combine like terms
3x +21 + 90 Subtract 21 from both sides
3x = 69 Divide both sides by 3
x = 23
14)
3x - 22 = 80 + x Subtract x from both sides
2x - 22 = 80 Add 22 to both sides
2x = 102 Divide both sides by 2
x = 51