What is the answer and how can I find it?

Question

Harry determined that every time he tapped his wand the sound increased 4 decibels. He noticed that after tapping his wand 3 times, the sound measured 34 decibels. Which equation best represents the sound when w represents a move of the wand and S represents the loudness of the sound?

A. s = 4w-22

B. s = 4w+22

C. s = 4w-43

D. s = 4w+43

(Please show your work!)

Answer 1

if each tap increases sound by 4, that means the slope, m=4

They tell you one data point (x,y) = (3,34)

Plugging all this into the equation y=mx+b, you can solve for b

34=4(3)+b

34=12+b Subtract 12 from both sides

34-12=12+b-12

b=22

The correct equation is: B. s = 4w+22