284 algebra De mystif ieD
(^) Worker Quantity Rate Time
Jeremy 1 1/60 60
Sarah 1 1/90 90
Together 2/3 2
3
23 2
3
t
tt
t
The equation to solve is^1
60
1
90
2
3
+=
t
. The LCD is 180t.
1
60
1
90
2
3
180 1
60
1
90
180 2
3
180 1
60
+=
+
=⋅
t
tt
t
t
+
=
+=
=
=
=
180 1
90
120
32120
5 120
120
5
24
t
tt
t
t
t
They will need 24 minutes to finish the lawn.
- (a) Let t represent the number of hours the presses need, working
together, to complete the job.
(^) Worker Quantity Rate Time
Press 1 1200 t 1200 t
Press 2 1500 t 1500 t
Together 45,000 45,000/t t
The equation to solve is 1200t + 1500t = 45,000. (Another equation
that works is 1200 + 1500 = 45,000/t.)
1200 1500 45 000
2700 45 000
45 000
2700
162
tt
t
t
t
+=
=
,
,
,
33