we have the system
2x+y=10
y=-2
step 1
Find out the intercepts
Line 1
2x+y=10
y-intercept ----> (0,10)
x-intercept ----> (5,0)
Line 2
y=-2
Is a horizontal line that passes through the point (0,-2)
step 2
Graph the given lines
see the attached figure
the intersection point is (6,-2)
that means
the solution is
x=6
y=-2
check the solution
substitute the value of x and y in equation 1
2x+y=10
2(6)+(-2)=10
12-2=10
10=10 ----> is true
that means ----> the solution is correct