A formula is an equation that represents a relationship between some structures or quantities or other entities. It’s a rule that uses mathematical computations and can be counted on to be accurate each time you use it when applied correctly.

The following are some of the more commonly used formulas that contain only variables raised to the first power. ✓ : The area of triangle involves base and height. ✓ I = Prt: The interest earned uses principal, rate, and time. ✓ C = 2πr: Circumference is twice π times the radius. ✓ : Degrees Fahrenheit uses degrees Celsius. ✓ P = R – C:

Profit is based on revenue and cost. When you use a formula to find the indicated variable (the one on the left of the equal sign), then you just put the numbers in, and out pops the answer. Sometimes, though, you’re looking for one of the other variables in the equation and end up solving for that variable over and over. For example, let’s say that you’re planning a circular rose garden in your backyard.

## Finally

You find edging on sale and can buy a 20-foot roll of edging, a 36-foot roll, a 40-foot roll, or a 48-foot roll. You’re going to use every bit of the edging and let the length of the roll dictate how large the garden will be. If you want to know the radius of the garden based on the length of the roll of edging, you use the formula for circumference and solve the following four equations