Three grades of milk are 1 percent, 2 percent and 5 percent fat by volume. If x gallons of the 1 percent grade, y gallons of the 2 percent grade, and z gallons of the 5 percent grade are mixed to give x+y+z gallons of a 3 percent grade, what is x in terms of y and z?  Pick one:  A) y + 3z  B) (y +z) / 4  C) 2y + 3z  D) z - 0.5 y  E) 3y + 4.5z
Based on the given information, the following equation could be dervied: 1% * x + 2% * y + 5% * z = 3% * (x+y+z) Then use algebra to figure out 2%*x = -1%*y + 2%*z. Thus, x = z - 0.5 y   z - 0.5 y
<result>D</result>
Three grades of milk are 1 percent, 2 percent and 5 percent fat by volume. If x gallons of the 1 percent grade, y gallons of the 2 percent grade, and z gallons of the 5 percent grade are mixed to give x+y+z gallons of a 3 percent grade, what is x in terms of y and z?