x+10y
3x+2y+(-2x)+8y
First of all you cannot substitute x with y, so what u do u make the numbers with the same letters they have,and I put -2x because + & - equals to -(minus) :-
3x-2x+2y+8y= x+10y
I don't add 1 to x coze when x alone stands for 1, I added +10y because both the y equations had + they were positive so I add a +.
