Answer:
600 minutes
Step-by-step explanation:
If we write both situations as an equation, we get:
y1 = 24 + 0.15x
y1 : total cost paid in first plan
x : total minutes of calls
y2 = 0.19x
y2 : total cost in second plan
x: total minutes of call
We are now looking for the situation where the total cost in the two plans is equal, so
y1 = y2
this gives
24 + 0.15x = 0.19x
<=> 0.04x = 24
<=> x = 600