Given:
Plan 1:
Charge for each minute = $0.19
Plan 2:
Monthly fee = $28
Charge each minute = $0.15
Let's determine when the costs of the two plans will be equal.
We have the following:
Equation for plan 1:
y = 0.19x
Equation for plan 2:
y = 0.15x + 28
Where x represents the number of minutes.
Now, to find when they will be equal, eliminate the equivalent sides y, then equate both expressions.

Let's solve for x.
Subtract 0.15x from both sides:

Divide both sides by 0.04:

Therefore, the two costs will be equal at 700 minutes.
ANSWER:
700 minutes