Question

Ravi is comparing the costs of long distance calling cards. To use card A, the cost is $0.50 to connect and then $0.05 per minute. To use card B, it costs $0.20 to connect and then $0.08 per minute. For what number of minutes would it cost the same amount (regardless of which card is used) for a single call?

Answer 1

Let m = number of minutes talked
The first card costs $0.05m + $.50 per call.
The second card costs $0.08m+$.20 per call

So, the costs are the same when these two equations are equal.
.05m+.5=.08m+.2
Subtract .2 from both sides to get
.05m+.3 = .08m
Subtract .05m from both sides to get
.3 = .03m
divide both sides by .03
10 = m

So the cost is the same if the call lasts for 10 minutes.

Answer 2

could you help me with another one @beans1992