Question

How can I do x+5y=10
-2x-6y=-8

Answer 1

Look for a term in either equation that has a coefficient of 1 in front of a variable, then solve for that variable.
e.g. in x + 5y = 10, x = 10-5y
now sub that into the other equation ....
-2(10-5y) - 6y = -8
-20 + 10y - 6y = -8
4y = 12
y = 3
back into x = 10-5y
x = 10 - 15 = -5

in this case, elimination would have worked just as simple

-2x - 6y = -8 ----> x + 3y = 4
subtract the first: x + 5y = 10
2y = 6, y = 3
in x+5y = 10
x + 15 = 10
x = -5

Answer 2

Eq1: x + 5y = 10
Eq2: -2x - 6y = -8
Multiply both sides ofEq1 by 2 and add the Eqs:
2x + 10y = 20
-2x - 6y = -8
Sum: 4y = 12,
Y = 3.
In Eq1, replace Y with 3 and solve for X:
x + 5*3 = 10,
X = -5.