Two-Step Equations
Undo the addition first, then the multiplication.
Concept
Peel the onion in reverse order
In 3x + 7 = 22, x was first multiplied by 3, then 7 was added. To get back to x you undo those steps in the opposite order.
So subtract the constant from both sides first, then divide by the coefficient. Order matters: dividing first forces you to divide the constant too.
ax + b = c ⟹ x = (c − b) / a