Question 106105
When you solve by subsitution, you use one equation to solve for one of the unknown variables and then substitute that solution in your other equation. 
1.{{{y=5x+5}}}
2.{{{y=15x-1}}}
Let's use equation 1 and substitute the value for y in equation 2. 
2.{{{y=15x-1}}}
{{{(5x+5)=15x-1}}} Substitute for y using Eq. 1. 
{{{5x+5-15x=15x-15x-1}}} Use the additive inverse of 15x. 
{{{-10x+5=-1}}}
{{{-10x+5-5=-1-5}}} Use the additive inverse of 5. 
{{{-10x=-6}}}
{{{-10x/(-10)=-6/-10}}} Multiplicative inverse of -10. 
{{{x=6/10}}}Simplify.
{{{x=3/5}}}Lowest terms. 
Now that you have a value for x, plug the value into either Equation 1 or Equation 2 and solve for y.
1.{{{y=5x+5}}}
{{{y=5(3/5)+5}}}
{{{y=3+5}}}
{{{y=8}}}
Always check your answers.
1.{{{y=5x+5}}}
{{{8=5(3/5)+5}}}
{{{8=3+5}}}
{{{8=8}}} 
Good answer.
2.{{{y=15x-1}}}
{{{8=15(3/5)-1}}}
{{{8=9-1}}}
{{{8=8}}}
Good answer. 
Your solution is x=3/5, y=8.