Question

the ratio of blue marbles to white marbles in a bag is 4 to 5 . at this rate, how many blue marbles are there if there are 15 white marbles

Answer 1

4/5 = B/W = B/15
B = 4*15/5 = 12

Answer 2

4:5 = x : 15
let x be blue marbles
4(15) = 5x
x = 12
therefore 12 blue marbles