A formula is very much like a set of instructions for converting variables into a solution.  Here is an example of a formula that expresses distance traveled in terms of the average speed and time of travel. The formula looks like this:

d = st

where:

d = the distance traveled

s = the average speed

t = the amount of time

If you know the speed and time of travel, the formula provides the exact instructions for finding the distance:  multiply the speed by the time. It's simply a matter of evaluating the expression — a formula in this case.

Example

A car travels an average speed of 45 miles per hour for 4 hours. How far does it travel in that time?

The desired formula is d = st.

Substituting the known values:  d = 45 x 4

Doing the math: d = 180 miles.

 

The formula for converting Centigrade temperatures to Fahrenheit is:

F = 1.8C + 32

where:

F = temperature in °F

C = temperature in °C

Example

Express 50°C to Fahrenheit.

The desired formula is F = 1.8C + 32°

Substituting known values: F = 1.8(50) + 32

Doing the math: F = 90 + 32 = 122

So: 50°C = 122°F