What is the number of degrees in the measure of the larger of two supplementary angles if the ratio of their measure is 4:5?
let the two angles be 4x and 5x (notice they are in the ratio 4:5)
but they are supplementary, so
4x + 5x = 180
9x = 180
x = 20
making 4x = 80, and 5x = 100
so the larger of the two angles is 100º