A girl scout was selling boxes of cookies. In a month, she sold both boxes of chocolate chip cookies ($1.25 each) and boxes of plain cookies ($0.75 each). Altogether, she sold 1,585 boxes for a combined value of $1,585.75. How many boxes of plain cookies did she sell? Pick one:	A) 0	B) 233	C) 500	D) 695	E) 791
Let #plain cookies sold be X then #chocolate cookies = (total cookies-X)   791quating for X   (0.75)*X +(1.25)*(1585-X)=1585.75   =&gt;x=791   791
<result>E</result>
A girl scout was selling boxes of cookies. In a month, she sold both boxes of chocolate chip cookies ($1.25 each) and boxes of plain cookies ($0.75 each). Altogether, she sold 1,585 boxes for a combined value of $1,585.75. How many boxes of plain cookies did she sell?