Problem

A formula is given along with the values of all but one of the variables. Find the value o...

A formula is given along with the values of all but one of the variables. Find the value of the variable that is not given. Use 3.14 as an approximation for π (pi). See Example.

EXAMPLE Using Formulas to Evaluate Variables
Find the value of the remaining variable in each formula.
(a) A = LW; A = 64, L = 10
As shown in FIGURE 7, this formula gives the area A of a rectangle with length L and width W. Substitute the given values into the formula.
FIGURE 7
The width is 6.4. Since 10(6.4) = 64, the given area, the answer checks.
(b)
This formula gives the area of a trapezoid. See FIGURE.
FIGURE
The length of the shorter parallel side, b, is 15. This answer checks, since , as required.