How do you solve $-20x+7y=137, 4x+5y=43$ ?

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Answer 1 · 2018-05-19T23:52:52

$x=-3$
$y= 11$

you have 2 equations and 2 unknowns so let's solve by elimination:

$-20x+7y = 137$
$" "4x+5y=43$

$-20x and 4x " have a common denominator "20x$ so multiply the bottom equation by 5:

$-20x+7y = 137$
$5(4x+5y=43)$

$-20x+7y = 137$
$" "20x+25y=215$

now add the equations together, notice the x terms cancel:

$32y = 352$

$y= 11$

finally insert y's value in to either of the original equations to solve for x:

$4x+5y=43$

$4x+5(11)=43$

$4x+55=43$

$4x=-12$

$x=-3$

How do you solve -20x+7y=137, 4x+5y=43-20x+7y=137, 4x+5y=43?