Answer:
7
Step-by-step explanation:
Let the width of the mechanical pencil lead be w_m and the width of a human hair be w_h. We are trying to find the number of widths of pieces of hair (let that be n) that make it equal to the width of a mechanical pencil lead, so we write the equation w_m=n*w_h. Hopefully, writing an equation makes this easier to understand!
Now, I want n, so I divide be w_h on both sides, substitute, and get that n = w_m/w_h = (7*10^-4)/(1*10^-4)
The 10^-4’s cancel, so we get n = 7/1 = 7.
I hope this helps! :)
