Question

Help me with this please

Answer 1

These are alternate interior and supplementary angles. to see which ones are equal, slide the (9x+12) down to the other intersection next to the 3x. Do you see that 3x and (9x+12) combine to make a straight line (supplementary, 180 degrees)? The angles across from each other are equal. So (9x+12) and (4y-10) are equal.

first solve for x
9x+12+3x = 180
12x+12 = 180
12(x+1) = 180
x+1 = 180/12
x+1=15
x = 14

now set the other angles equal
9(14) + 12 = 4y -10
126 + 12 = 4y - 10
138 = 4y - 10
138 + 10 = 4y
148 = 4y
148/4 = y
37 = y