Find the solution of this system of two linear equations using substitution 11x+3y=103 and y =3x+1

11x+3y=103 and y=3x+1. 

11x+3(3x+1)=103  > plug in (3x+1) for y in the first equation.  You will want to distribute the 3 to the 3x+1 to get something that looks like:

11x+9x+3=103    > now you want to combine like terms 

20x+3=103 ---> subtract 3 from both sides
20x=100   > divide both sides by 20
x=5    

y=3(5)+1     ---> I like to plug in this to the equation that already has y isolated.  3*5 is 15, add 1 and you find that y=16.

(5, 16) will be your final answer (: