Question

Harriet is comparing the costs of calling cards. To use card A, the cost is $1.00 to connect and then $0.04 per minute. To use card B, it costs $0.65 to connect and then $0.06 per minute. For what number of minutes does it cost the same amount to use each card for a single call? (Enter only the number.)

Answer 1

Card A costs

A=1 + .04m, where m is minutes

Card B costs

B=.65 + .06m, where m is minutes

At some point, A=B. Just equate these two equations and solve for m to see when this condition happens:

Answer 2

Make sense?

Answer 3

Um... a little @ybarrap

Answer 4

$$
A=B\\
\implies 1 + .04m=.65 + .06m\\
\text{ So, }\\
1-0.65=.06m-0.04m=m(0.06-0.04)\\
\implies m=\cfrac{1-0.65}{0.06-0.04}
$$
At this value of \(m\), \(A=B\).