Question

The table shows how much Li earns for moving different numbers of lawns. Write an algebraic expression that describes the total earnings for n lawns.

Answer 1

15n

Explanation:

Given

The above table

Required

The formula of the table

First, calculate the slope (m)

`m = (y_2 - y_1)/(n_2 - n_1)`

Where:

n = Number of Lawns

y = Earnings

`(n_1,y_1) = (2,30)`

`(n_2,y_2) = (5,75)`

So, we have:

`m = (75 - 30)/(5 - 2)`

`m = (45)/(3)`

`m = 15`

The equation is then calculated as:

`y = m(n- n_1) + y_1`

This gives:

`y = 15(n- 2) + 30`

`y = 15n- 30 + 30`

`y = 15n`

Hence:

B is correct