Question 129270
2x-3y=12      x=4y+1 you would add what x equals in the place of x and solve 

2*4y+1-3y=12 take all the numbers with letters next to it and add,subtract,divide,or multiply the numbers 2*1y+1=12 then drop the one and it just becomes y now add the numbers 2 and 1 that would become 3y=12 now divide each side by 3 to get rid of the 3 next to y cause dividing number will cause multiplication to cancel it out come up with answer 4
                            check answer                       
2x-3y=12                    3*4=12  
2*4y+1-3y=12
2*y+1=12
3y=12
3y/3=12/3
y=4