An algebraic formula links quantities, e.g. $A = l \times w$ (area of a rectangle) or $v = u + at$.
To use a formula, substitute the known values. For $v = u + at$ with $u = 2$, $a = 3$, $t = 4$: $v = 2 + 3 \times 4 = 14$. We can also change the subject to make a different letter the focus.
Remember
- Substitute values carefully, following order of operations.
- Changing the subject rearranges the formula.