Question

solve by substitution
1/3x+1/5y=-4/5
1/3x+2y=10

Answer 1

Simplest is to note that the second equation converts to 1/3x = 10- 2y and replace 1/3x in the first equation. Then solve for y and compute x.

Answer 2

(1/3)x+(1/5)y=-4/5
(1/3) x+2y=10
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(1/3) x =10 - 2y


10 - 2y + (1/5)y=-4/5 after subsitution

See if you get x = -6 and y = 6.