Question

in a department sore there are red t-shirts, blue t-shirts, and yellow t-shirts. 3/7 of the shirts are red, 1/3 are blue and the rest are yellow. if there were 20 more red than blue, how many were yellow?

Answer 1

let the total t-shirts be x
then,
RED:3x/7

BlUES:x/3

Yellow: x-(3x/7 +x/3)=5x/21

we know reds are 20 more than blues
therefore, 3x/7 =(x/3 +20)
then solve for x by subtracting x/3 both sides
(3x/7)-(x/3)=20
(2x/21)=20 ,multiply 21 both sides to eliminate the denominator ,then you will get,

2x=420

x=210(total t-shirts sold in the store)

we know the yellows are 5x/21
substitute x in 210.
therefore,yellows are (5.210)/21
Yellow= 50