posted by Anonymous on .
in a department store, there were a certain number of red t-shirts, blue t-shirts and yellow t-shirts. 3/7 of the t-shirts were red, 1/3 of them were blue, and the rest were yellow. If there were 20 more red t-shirts than blue t-shirts, how many yellow t-shirts were there?
X = the total # of t-shirts.
3x/7 = the # of red t-shirts.
x/3 = the # of blue t-shirts.
(3x/7-20)=The # of blue t-shirts,also.
x/3 = 3x/7 - 20,
x/3 - 3x/7 = -20,
Multiply both sides by 21:
7x - 9x = -420,
-2x = -420,
X = 210.
3x/7 = 3*210 / 7 = 90 Red t-shirts.
x/3 = 210 / 3 = 70 Blue t-shirts.
Y = 210 - 90 - 70 = 50 Yellow t-shirts.