A 22 inch candle burns at a constant rate of 1.2 inches per hour. Write a formula that expresses L, the length of the candle in inches, in terms of t, hours since the candle started burning.
You can build a formula like above using the rule of three. If we burn 1.2 inches in 1h how much L inches we burn in t hours? And we get L = 1.2*t. Easy right?