A formula is really just an equation. We call it a formula to emphasise that it applies for values that we are interested in. For instance P=2l + 2w is the formula for the perimeter of a rectangle with length l and width w.

Worked Example

1.) A tin contains P peas. There are N tins. Derive a formula for T, the total number of peas in all of the tins.

2.) Derive a formula to convert US dollars ($) into Euros (€) if the exchange rate is €1.40:$1

Exercise 1

Once we know what a formula is, we can then substitute in values.

Worked Example

Derive a formula to convert dollars, D, into Egyptian pounds, E, if the exchange rate is 6 Egyptian pounds for each dollar. Use this formula to convert $350 into Egyptian pounds.

Exercise 2

Answers to both exercises