Question

3. Sam and Tim each have savings accounts. Every month they each put in some of their
earnings from mowing lawns. Use the tables to find the y-value of the solution to the
system shown.
х
1
2
3
4
f(x)
80
110
140
170
х
1
2
3
4
g(x)
100
120
140
160

Answer 1

Answer:

$y = 30x +50$ --- Sam

$y = 20x +80$ --- Tim

Step-by-step explanation:

Given

Sam                         Tim

х  --- f(x) ---------------  g(x)

1  --- 80   --------------- 100

2  --- 110  --------------- 120

3  --- 140 --------------- 140

4 --- 170 -------------- 160

Required

Determine the y value

y value implies the equation of the table

Calculating the equation of Sam

First, we need to take any corresponding values of x and y

$(x_1,y_1) = (1,80)$

$(x_2,y_2) = (4,170)$

Next, we calculate the slope (m)

$m = \frac{y_2 - y_1}{x_2 - x_1}$

$m = \frac{170 - 80}{4 - 1}$

$m = \frac{90}{3}$

$m = 30$

Next, we calculate the line equation using:

$y - y_1=m(x-x_1)$

$y - 80 = 30(x - 1)$

$y - 80 = 30x - 30$

Make y the subject

$y = 30x - 30 + 80$

$y = 30x +50$

Calculating the equation of Tim

First, we need to take any corresponding values of x and y

$(x_1,y_1) = (1,100)$

$(x_2,y_2) = (4,160)$

Next, we calculate the slope (m)

$m = \frac{y_2 - y_1}{x_2 - x_1}$

$m = \frac{160 - 100}{4 - 1}$

$m = \frac{60}{3}$

$m = 20$

Next, we calculate the line equation using:

$y - y_1=m(x-x_1)$

$y - 100 = 20(x - 1)$

$y - 100 = 20x - 20$

Make y the subject

$y = 20x - 20+100$

$y = 20x +80$