SOLUTION: Hi guys just want to ask on how to get x and y in this equation. 40x+35y=20,000 and 70x+90y=40,000. Hope you could help! I just want to know how to solve it thank you!

Algebra ->  Equations -> SOLUTION: Hi guys just want to ask on how to get x and y in this equation. 40x+35y=20,000 and 70x+90y=40,000. Hope you could help! I just want to know how to solve it thank you!      Log On


   

Question 1048839: Hi guys just want to ask on how to get x and y in this equation. 40x+35y=20,000 and 70x+90y=40,000.
Hope you could help! I just want to know how to solve it thank you!
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

40x%2B35y=20000....eq.1
70x%2B90y=40000.....eq.2
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start with
40x%2B35y=20000....eq.1 ....solve for x
40x=20000-35y
x=20000%2F40-35y%2F40
x=500-%2835%2F40%29y........substitute in eq.2


70%28500-%2835%2F40%29y%29%2B90y=40000......solve for y

35000-%28%2835%2A70%29%2F40%29y%2B90y=40000
35000-%28%287%2A70%29%2F8%29y%2B90y=40000
35000-%28490%2F8%29y%2B90y=40000
90y-%28490%2F8%29y=40000-35000
%28720%2F8%29y-%28490%2F8%29y=5000
%28230%2F8%29y=5000
y=5000%2F%28230%2F8%29
y=40000%2F230

highlight%28y=4000%2F23%29
now find x

x=500-%2835%2F40%29%284000%2F23%29

x=500-%2835%2A4000%29%2F%2840%2A23%29
x=500-%2835%2A100%29%2F23
x=%28500%2A23%29%2F23-3500%2F23
x=11500%2F23-3500%2F23
x=%2811500-3500%29%2F23
highlight%28x=8000%2F23%29

so, exact solutions are: x+=+8000%2F23, y+=+4000%2F23