<PRE><B>Question 29632</B>
Let there be X D.Fir trees
Then there are 850-X Pine trees
The Fir trees cost $300 each so total = 300X
The pine trees cost 225 each so total cost = 225(850-X)
Sum total 
300X+225(850-X) = 217500
Dividing on both sides with 75
4X+3(850-X) = 2900
4X+2550-3X = 2900
X+2550= 2900
Subtracting 2550 0n both sides
X = 350
which means there are 500 pine trees</PRE>