Answer:
350 Douglas fir, 500 Ponderosa pine
Step-by-step explanation:
Let f = the number of fir trees
and p = the number of pine trees.
Then, we have two conditions:
(1) f + p = 850
(2) 300f + 225p = 217 500
(3) p = 850 -f Subtracted f from each side of (1)
(4) 300f + 225(850 - f) = 217 500 Substituted (3) into (3)
300f + 191 250 - 225f = 217 500 Distributed 225
75f + 191 250 = 217 500 Distributed the 7
75f = 26 250 Subtracted 191 250 each side
(5) f = 350
350 + p = 850 Substituted (5) into (1)
p = 500 Subtracted 350 from each side
The company bought 350 fir trees and 500 pine trees.
Check:
(1) 350 + 500 = 850 (2) 300 × 350 + 225 × 500 = 217 500
850 = 850 105 000 + 112 500 = 217 500
217 500 = 217 500
OK.
