Remember that in these diagrams, adjacent angles form a straight angle, which adds to 180 degrees. Also, vertical angles are always the same measure.
17.
11x+16+8x+12=180
19x+28=180
19x=152
x=8
3y+13+5y-1=180
8y+12=180
8y=168
y=21
18.
3x+17=5x-47
3x+64=5x
64=2x
32=x
2y+9=3y-20
9=y-20
29=y
