Patrick W. answered 03/31/15
Tutor
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High School Mathematics Teacher, Passionate Math Geek
You picked 50 total bushels, some apples, and some oranges. Let's call them P for apples and R for oranges
P+R=50
You paid $2 per bushel of apples and $3 per bushel of oranges, totalling $120
2P+3R=120
Now we have a system of equations:
P+R=50
2P+3R=120
I'm going to use elimination by multiplication. I'm going to multiply my first equation by two, then subtract it from my second equation. That way, I see that my P variable will be cancelled out:
2P+2R=100
2P+3R=120
1R=20
R=20 bushels
If I picked 20 bushels of oranges, I must have picked 30 bushels of apples. I can also double check this by plugging it back in to my other equation:
$2(30)+$3(20)
$60+$60
$120