A formula connects variables, and the subject is the letter that already stands alone on one side of the equals sign. In the formula $A=lw$, the subject is $A$.

When you are asked to make $x$ the subject, your final line should have $x$ alone, usually on the left of the equals sign. Changing the subject is like solving an equation, but with letters instead of numbers.

Use the balance idea all the way through the process. Do not just "move" a term and hope the sign changes; instead, undo operations in reverse order on both sides to isolate the variable.