solve ax - 5 = b for a

Answer 1

a times a number - 5 = b so, add 5 to both sides

ax-5 = b
+5 +5 so now you have ax = b+5
divide both by x and you get a so ...
a=(b+5)/x

Answer 2

|y|=9

Answer 3

|y|=9
9 -9