Question 63299
Let us construct the equation fro the given equations, 

Amount for 600 minutes + extra minute *  amount for each minute =  total amount 

$49.99 +  150 * 0.35 =  total amount

49.99 + 52.5 = total amount

102.49 = total amount

Therefore the customer has to pay $102.49


Reason

Given 600 minutes are free, so we have'

750 minutes, 

So the extra minutes is 150