Can I get some help please?

A

Step-by-step explanation:

A linear function is described as:

https://tex.z-dn.net/?f=f(x)%20%3D%20ax%20%2B%20b

When the value of x = 0, then you're left with

https://tex.z-dn.net/?f=f(x)%20%3D%20b

In this question, the speed of sound is the linear function while the temperature is the independent variable. When T = 0, you're left with

https://tex.z-dn.net/?f=S(0)%20%3D%20331.4

Which means the speed of sound in air when temperature is 0°C is 331.4m/s.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18