The caps is a bit unnecessary
by substitution, so you need to take one of the equations, solve for x or y, and then plug that equation into the other equation and solve for the remaining variable
lets use the first eq and solve for y
2x=10-y
y+2x=10
y=10-2x
now we substitute this equation into the other
3x-y=5
3x-(10-2x)=10
distribute the negative 1
3x-10+2x=10
add like terms
5x-10=10
5x=20
divide by 5 to both sides
x=4
now, once you have x (or y if you solved for x), you can substitute it back into one of the equations in order to solve for y.
Substituting it into the first eq
2(4) =10-y
8=10-y
y=2
so the solution to the system of eqs is
x=4
y=2
and thats substitution in a nutshell
