In order to have a linear function, the rate of change needs to be the same in each point
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2023/formulas/mathematics/high-school/78uaqhwt0aws3qfwxigaftpihnmb1gzxtp.png)
For
(-18,2)=(x1,y1)
(-14,4)=(x2,y2)
![m=(4-2)/(-14+18)=(1)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/83ksnl4jnqr3dm996jovph70taq3rdrfmy.png)
for
(-14,4)=(x1,y1)
(-12,5)=(x2,y2)
![m=(5-4)/(-12+14)=(1)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/v93u2agftkdt3hfk3utllv92pqexm49o2q.png)
for
(-12,5)=(x1,y1)
(0,12)=(x2,y2)
![m=(12-5)/(0+12)=(7)/(12)](https://img.qammunity.org/2023/formulas/mathematics/college/oxjvgc1h1jbm8ci1rhfwsgf64tj5pjht3z.png)
as we can see here are the two numbers so we will obtain the equation in order to know the number that needs to be change
![y=(1)/(2)x+11](https://img.qammunity.org/2023/formulas/mathematics/college/17znzlune7zsa7dodeh162g5xxxhu2tk1u.png)
therefore if x=0
![y=(1)/(2)(0)+11=11](https://img.qammunity.org/2023/formulas/mathematics/college/7n44wy9ymeu5l5656cunkvo863yxojwa6s.png)
the number we need to change is 12 and need to be changed for 11
(0,11)
a. The number that needs to be changed in order to create a linear function is 12
b. That number needs to be changed to 11 in order for the function to be linear