Answer:
$49.99
Explanation:
Total amount paid by Sara and Martin was $1319.90
So each of them paid 1319.90/2 = $659.95
Out of this $59.99 was the initial fee. So the total monthly fees each paid for 12 months = 659.95-59.99 = $599.96
Since this is monthly fees paid for 12 months, monthly fee = 599.96/12 = 49.996 which can be rounded down to $49.99 per month. (If rounded up it is $50 per month)
In equation form, if X is the monthly fee, then total paid by 2 people = 2(59.99 + 12X) = 1319.90
Dividing each side by 2 we get 59.99 + 12X = 1319.90/2 = 659.95
Subtracting 59.99 on both sides gives 12X = 659.95-59.99 = 599.96
Dividing by 12 both sides gives
X = 599.96/12 = 49.99
which is the same as the first approach