Elvin's monthly telephone bill is the sum of the charge for the calls he made during the month and a fixed monthly charge for Internet service. Elvin's total telephone bill for January was $48 and Elvin's total telephone bill for February was 90$. If Elvin's charge for the calls he made in February was twice the charge for the calls he made in January, what is Elvin's fixed monthly charge for Internet service? Answers.
A) $5 B) $10 C) $14 D) $6 E) $28
Bill = Fixed Charge + Charge of Calls made   in Jan, Bill = Fixed Charge(Let, y) + Charge of calls made in Jan (Let, x) = $48   in Feb, Bill = Fixed Charge (Let, y) + Charge of calls made in Feb (Then, 2x) = $90   i.e. x+y = 48   and 2x+y = 90   Take the difference if two equations   i.e. (2x+y) - (x+y) = 90 - 48   i.e. x = 42   i.e. Fixed Monthly Charge, y = 6   Answer: Option   $6
<result>D</result>
Elvin's monthly telephone bill is the sum of the charge for the calls he made during the month and a fixed monthly charge for Internet service. Elvin's total telephone bill for January was $48 and Elvin's total telephone bill for February was 90$. If Elvin's charge for the calls he made in February was twice the charge for the calls he made in January, what is Elvin's fixed monthly charge for Internet service?