Chapter 8 linear appliCaTionS 233
- 18 18
18
18
18 10
1810
180
18
10 1000
()
.()
%
x
x
x
x
=
=
=
===
18 is 1000% of 1.8.
- 2 1
4
1
2
1
4
1
8
0 125 125
x
x
x
=
=⋅
==..= %
41 is 12.5% of 2.
8.
1
4
2
42
8 800
x
x
x
=
=
==
()
%
2 is 800% of^14.
Working with Formulas
For some word problems, nothing more is required other than to plug a given
value into a formula, which is either given or is readily available. The most dif-
ficult part of these problems is to decide which variable the given quantity
should represent. For example, the formula might look like R = 8q and the
value given to you is 440. Is R = 440 or is q = 440? The answer lies in the way
the variables are described. In R = 8q, suppose R represents revenue (in dollars)
and q represents quantity (in units) sold of some item. In the question, “If
440 units were sold, what is the revenue?” q is 440. We would then solve
R = 8(440). In the question, “If the revenue is $440, how many units were
sold?” 440 is R, and we would solve 440 = 8q.