Let
x--------> the speed of the girl in step
y--------> the speed of the escalator in step
d------> the distance between ground and floor.
we know that
when the girl is going up on escalator
----> equation
when the girl is going down on escalator
-------> equation
Adds equation and equation
--------> equation
Time to climb (in step) with y=0 (escalator standing still)
-----> equation
Substitute equation in equation
therefore
the answer is
Answer:
250 minutes of calling will cost same using both plans.
$53
Step-by-step explanation:
Please consider the complete question.
A phone company offers two monthly plans. Plan A costs $23 plus an additional $0.12 for each minute of calls. Plan B costs $18 plus an additional $0.14 of each minute of calls. For what amount of calling do the two plans cost the same? What is the cost when the two plans cost the same?
Let x represent the number of call minutes.
The total cost of calling for x minutes using plan A would be cost of x minutes plus fixed charge that is .
The total cost of calling for x minutes using plan B would be cost of x minutes plus fixed charge that is .
To find the number of minutes for which both plans will have same cost, we will equate total cost of x minutes for both plans and solve for x.
Therefore, calling for 250 minutes will cost same using both plans.
Upon substituting in expression
, we will get:
Therefore, the cost will be $53, when the two plans cost the same.