Answer:
[tex]\boxed{\boxed{\pink{\bf \leadsto The \ price \ of \ a\ 18 \ min \ call \ is \ \$ \ . }}}[/tex]
Step-by-step explanation:
According to Question ,The price of a 7-minute phone call is $2.45 . And we need to find the price of a18 minute phone call . So we will use unitary method here ,
[tex]\implies\bf Cost \ of \ 7 \ min. \ phone \ call \ is\ \$ \ 2.45 . \\\\\implies \bf Cost \ of \ 1 \ min. \ phone \ call \ will \ be \ \dfrac{\$ 2.45}{7} \\\\\implies \bf Cost \ of \ 18 \ min. \ phone \ call \ will \ be \ \dfrac{\$ 2.45}{7} \times 18 = \red{\$ 6.3 } [/tex]
Hence the cost of 18 minutes call is $ 6.3 .
Here it was a case of direct proportion in which if two things are directly proportional to each other. If one thing thing increases then the value of second also increases. Here if the time increases then the cost also increases.
