Question 158166
Let the angle be A, then its supplement would be 180-A.  The problem description states that the ratio of these two is 3:7, so...
{{{A/(180-A) = 3/7}}} Cross multiply.
{{{7A = 3(180-A)}}} Simplify.
{{{7A = 540-3A}}} Add 3A to both sides.
{{{10A = 540}}} Divide both sides by 10.
{{{A = 54}}}degrees.
Now you are to show the ratio of the angle A to its complement.
The complement of angle A is 90-A, so the ratio is:
{{{A/(90-A) = 54/(90-54)}}} = {{{54/36 = highlight(3/2)}}}