When making a telephone call using a calling card, a call lasting 3 minutes costs $0.85. a call lasting 10 minutes costs
minutes using a calling card. write a linear equation that models the cost of making a call lasting x minutes
let y be the cost of making a call lasting x minutes using a calling card. write a linear equation that models the cost of making a call lasting x mins

ANSWER:  

The linear equation that models the cost of making a call lasting x mins is y = 0.2834x.

SOLUTION:

Given, when making a telephone call using a calling card, a call lasting 3 minutes costs $0.85.

we need write a linear equation that models the cost of making a call lasting x minutes.

Let y be the cost of making a call lasting "x" minutes using a calling card.

Then, y = cost of making call per minute x minutes

Now, cost of making call per minute can be obtained from the case we have i.e. $0.85 per 3 minutes

Cost of call per minute =

Cost of call per minute =

Cost of call per minute = 0.2834

cost of call per minute is $0.2834 approximately

Now, y = 0.2834 × x

y = 0.2834x

hence, the linear equation that models the cost of making a call lasting x mins is y = 0.2834x.