Need an explanation on how to do​

substitute y in the other equation

Step-by-step explanation:

so for 10.1 substitute the x+3 in for y in y+x+1 bc thats what the first equation tells you. So then you would have x+3=x+1, so then you would solve and would get x+2=x which is obviously not true so you would say : the lines intersect or whatever your teacher said to say

but if the equation is true then you plug that variable in for either of the equations and then you have the other variable (sorry if that makes no sense)