Chapter 8 linear appliCaTionS 273The equation to solve is^1
45
1
30+ = ^1.
tThe LCD is 90t.1
451
30190 1
451
3090 190 1
45+=
+
=
t
tt
tt
+
=+=
=
=
=90 1
30902390
590
90
5
18ttt
t
t
tJoe and Jerry can mow the lawn in 18 minutes.
Tammy can wash a car in 40 minutes. When working with Jim, they can
wash the same car in 15 minutes. How long would Jim need to wash the car
by himself?
Let t represent the number of minutes Jim needs to wash the car by himself.
Worker Quantity Rate Time
Tammy 1 1/40 40
Jim 1 1/t t
Together 1 1/15 15The equation to solve is^1
40
11
15+ = .
tThe LCD is 120t.1
4011
15
120 1
401 120 1
15
120 1
40+=+
=
t
t
ttt
+
=+=
−−
=120 1 83 120 8
33
120 5
120t
tttt
tt
t55
24=
=t
t