Math HW help? Please Explain how its done?

Question

Use elimination to solve the system of equations:

10x-4y=-20 and 10x-5y=-35

Answer 1

x terms would cancel out if only they'd had opposite signs.

So, multiply the one of the equation by -1 and add the equations and eliminate the varaible x.

Multiply the equation 2 by -1.

10x - 5y = -35 ---------> -10x + 5y = 35

Now, add the equations

10x - 4y = -20

-10x + 5y = 35

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                    y = 15

substitute y = 15 in equation 10x -5y = -35.

10x - 5 * 15 = -35

10x - 75 = -35

Subtract 75 from each side.

10x = 40

Divide each side by 10.

x = 4

(x, y) = (4, 15).