In an art class of 84 students, 0.125 of the girls passed the drawing test and 4/5 of the boys passed the drawing test. A total of 24 students passed the drawing test. How many girls failed the drawing test?
g+b = 84, so
1/8 g + 4/5 (84-g) = 24
g = 64
7/8 of them failed, or 56
0.125 g + 0.8 b = 24
b + g = 84
so
b = (84-g)
0.125 g + 0.8( 84-g) = 24
0.125 g + 67.2 - .8 g = 24
43.2 = 0.675 g
g = 64 girls total
(1 - 0.125) 64 = 56 failed