Question 549460
Supplementary is when two angles add up to be 180 degrees (and form a straight line)
Complementary is when they add up to 90 degrees

So if our angle is y
we know that 180-y=30+4*(90-y)
*[invoke explain_simplification "180-y=30+4*(90-y)" ]
So we find y=70
but we are asked for the complementary angle so that would be 90-y or 20 degrees