we have a few steps to figure the complement of ∠KMA. We know what is given will equal a straight line so we set the two expressions to equal 180.
(2x - 3) + (7x + 21) = 180
2x - 3 + 7x + 21 = 180 (combine like terms)
9x + 18 = 180 (subtract 18 from both sides)
9x = 162 (divide both sides by 9)
x = 18 (use this to find the value of ∠KMA)
2x - 3
2(18) - 3
36 - 3
33 ∠KMA is 33°
to find the complement, we subtract the 33 from 90 and we get the complement to ∠KMA is 57°
