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 $1,586.75. How many boxes of plain cookies did she sell?  Choose the most appropriate option
A) 0 B) 233 C) 500 D) 695 E) 789
Let #plain cookies sold be X then #chocolate cookies = (total cookies-X)   789quating for X   (0.75)*X +(1.25)*(1585-X)=1586.75   =&gt;x=789
<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 $1,586.75. How many boxes of plain cookies did she sell?