A bag contains 4 blue, 5 green and 3 red marbles. How many green marbles must be added to the bag so that at least 79 percent of the marbles are green?
suppose you add x green marbles
greentotal=5+x4+3+5+x=5+x12+x=0.79
multiply both sides by 12+x
5+x=9.48+0.79x
0.21x=4.48
x=21.¯3
You need to add at least 21.¯3 green marbles, but that doesnt make sense here, since you can't have a fractional amount.
Rounding up, at least 22 green marbles must be added
