two angles, a and b are complementary if the sum of their measure is 90 degrees. If angle a is 21 degrees more than twice angle b find the measures of angles a and b. I would like to know how to set this equation up in order to find the answer.

Answer 1

The question defined what complementary angles are, but did not say that a and b are complementary.
The question has a solution if a and b are complementary, and will be assumed as follows.

if a and b are complementary, then
a+b=90

angle a is 21 degrees more than twice angle b means
a=21+2b

So with the two equations, you can solve for the two unknowns a and b.