PREP模考题求助

Vickyliu

3 grades of milk are 1%, 2% and 3%  fat by volume. if x gallons of the 1% grade, y gallons of the 2%, and z gallons of the 3% are mixed to give x+y+x gallons of a 1.5% grade. what is x in terms of y and z?
A. y+3z
B. (y+z)/4
C. 2y+3z
D. 3y+z
E. 3y+4.5z
ANSWER: A
请求各路大侠的帮助

queenie924

You got a typo in the question. x+y+z gallons

1x + 2y +3z = 1.5x +1.5y +1.5z

0.5y + 1.5z = 0.5x

x = y + 3z

Vickyliu

谢谢你帮我理清了这道题的思路。