A branch of mathematics that uses variables is algebra
The answer is the last one because you are plugging the x values in for x and solving it out for y.
Interior angles of a triangle add up to 180
< X + < Y + < Z = 180
68 + Y + 90 = 180
158 + Y = 180
Y = 180 - 158
Y = 22 <==
7) 31, 27, 12, 10, 0, -4, -19, -27, -203
8) 78, 32, 9, -5, -18, -24
9) 90, 11, 5, -5, -47, -50, -62
10) 24, 19, 8, 6, 1, 0, -2, -8, -9, -15
11) 12, 8, 7, -1, -13, -20
12) 14, 7, 6, 0, -3, -5, -8, -25
The answer will be 67/100.