Question

The function 56 – 4y = –5x can be used to determine the total amount of money in a coin jar, y, after money is added for x days. What is the rate of change in dollars with respect to the number of days? $11.20 per day $1.25 per day $14.00 per day $0.80 per day

Answer 1

$1.25 per day

Explanation:

Given

`56- 4y = -5x`

Required

Determine the rate of change

To do this; first, we make y the subject

`56- 4y = -5x`

`-4y = -5x - 56`

Multiply through by -1

`-1*-4y = -1*(-5x - 56)`

`4y = 5x + 56`

Divide through by 4

`(4y)/(4) = (5x)/(4) + (56)/(4)`

`y = 1.25x + 9`

An equation is generally represented as:

`y = mx + b`

Where m represents the rate of change.

By comparison:

`m = 1.25`

Hence, the rate is $1.25 daily