u need two equations.x + y = 125
0.60x + 0.30y = (0.36)(125)
x + y = 125
0.60x + 0.30y = 45
solve for a variable in the first equation
y = 125 - x
plug into the second equation
0.60x + 0.30(125 - x) = 45
0.60x + 37.5 - 0.30x= 45
0.30x + 37.5 = 45
0.30x = 7.5
x = 25
plug the answer for x into the first equation
25 + y = 125
y = 100
