The ratio of boys to girls in a math class is 5 to 3. When 3 girls and 1 boy join the class, the ratio becomes 4:3. What is the least possible number of students in the class after the new students join?

1 answer

let number of boys be 5x
let numbe of girls be 3x

after change:
boys --- 5x+1
girls --- 3x+3

(5x+1)/(3x+3) = 4/3
15x + 3 = 12x + 12
3x = 9
x = 3

new class :
boys = 16
girls = 12
total = 28