An overseas phone call is charged at one rate for the first minute and at a different rate for each additional minute. If a 7 minute call costs $10 and a 4 minute call costs $6.40, find each rate.

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aruv | High School Teacher | (Level 2) Valedictorian

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An overseas phone call is charged at one rate for the first minute and at a different rate for each additional minute. If a 7 minute call costs $10 and a 4 minute call costs $6.40, find each rate.

Let call charge for the first minute be  $x, and each additional minute be $y.

By given conditions,

x+6y=10       (i)

x+3y=6.40    (ii)

Subtract (ii) from (i), we have

3y=3.60

y=1.20           (iii)

Substitute y from (iii) in (ii),

x+3.60=6.40

x=6.40-3.60

x=2.80

Thus call rates are for first minute $2.80 and each additional minute $1.20 .

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