求PREP-PS-1-38 解

jesuisdesole

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 ?

 

(A) y + 3z

(B) 

(C) 2y + 3z

(D) 3y + z

(E)

ANS: A

谢谢

suomaliren

(x+y+z)1.5=x+2y+3z

0.5x=0.5y+1.5z

x=y+3z