Answer :
angles add to 180 since assume straighe line
x+y=180
x=2n+12
y=3n+18
2n+12+3n+18=180
5n+30=180
minus 30
5n=150
divide 5
n=30
sub back
x=2n+12
x=2(30)+12
x=60+12
x=72 degrees
C
x+y=180
x=2n+12
y=3n+18
2n+12+3n+18=180
5n+30=180
minus 30
5n=150
divide 5
n=30
sub back
x=2n+12
x=2(30)+12
x=60+12
x=72 degrees
C