Ok so if you notice every choice is solved for a, all you have to do is isolate "a" in 7a-8b=10x. Start by moving 8b to the other side and to change the sign. Now it is 7a = 10x + 8b. Then divide everything by 7 and you get a = (10x + 8b)/7
What do you mean by that i mean yeah you can have as many as needed to subtract
