pp-t1-ps-38

[yiyiyi]

Three grades of milk are 1 percent, 2 percent, and 3 percent fat by volume. If x gallons of the 1 percent grade, y gallons of the 2 percent grade, and z gallons of the 3 percent grade are mixed to give x + y + z gallons of a 1.5 percent grade, what is x in terms of y and z ?

ans
(A) y + 3z

[sunnyblue13s]

(1*x+2*y+3*z)/(x+y+z)=1.5

則....x=y+3z