SOLUTION: 7x+8y=25 9x+10y=35 using substitution or elimination

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Question 914585: 7x+8y=25
9x+10y=35 using substitution or elimination
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Substitution: Pick an equation; either equation. Solve for one of the variables in terms of the other. Substitute this expression in the other equation and solve for the value of the single variable.
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Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

7x+8y=25
9x+10y=35 using substitution or elimination


7x +  8y = 25 ------- eq (i)

9x + 10y = 35 ------- eq (ii)

- 35x - 40y = - 125 ------- Multiplying eq (i) by - 5 ------ eq (iii)

  36x + 40y =   140 ------- Multiplying eq (ii) by 4 ------- eq (iv)

    x = 15 ------ Adding eqs (iii) & (iv)

Now substitute 15 for x in eq (i) or eq (ii), or any of the other equations to determine the value of y