1. Solving equations that involve formulas.

2. A formula is an algebraic equation that relates two or more quantities.
Distance
distance = rate • time
Perimeter
triangle
A measure of the distance around a geometric figure.
rectangle
Area
rectangle
square units of the interior region of a two dimensional figure or the surface of a three dimensional figure.
triangle

3. The truck traveled 390 miles.
Example 1 Use a variable expression to find the distance traveled by a truck moving at an average speed of 65 miles per hour for 6 hours.
1.Write the formula.
d = rt
2. Substitute.
= (65)(6)
3. Simplify.
= 390
4. Write a sentence.
The truck traveled 390 miles.
Note: Include the label in your sentence.
Use one equal sign per line of work. Keep the equal signs in a line!

4. Example 2 Find the perimeter of a triangle with two sides 5 miles long and one side 3 miles long.
1. Write the formula.
P = a + b +c
2. Substitute.
= (5) + (5) + (3)
3. Simplify.
= 13
4. Write a sentence.
The triangle has a perimeter of 13 miles.
Check if you used one equal sign per line of work. Are the equal signs in a line?

5. Example 3 Find the area of a triangle with base 15 centimeters and height 8 centimeters.
1. Write the formula.
2. Substitute.
3. Simplify.
= 60
4. Write a sentence.
The area of the triangle is 60 square centimeters.
The area of the triangle is 60 cm2.
You cannot write 602 cm.