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

m = the number of minutes used talking.
The first card costs $0.05m + $0.50 per call
The second card costs $0.08m + $0.20 per call.

Costs are same when two equations are equal.

.05m + .5 = .08m + .2

Subtract .2 from both sides

.05 + .3 = .08m

Now, subtract .05m from both sides

.3 = .03m

Now divide both sides by .03

10 = m

Your answer is 10. The cost will be the same if both last for 10 minutes.

Hope this helps you! :)

Answer 2

* the first equation is wrong, sorry about it should be

.05m + .5 = .08m + .2