How is the graph of y= 1/3x related to its parent function y=1/x

Vertical contraction: g (x) = k · f (x)
 When you multiply the y coordinate of the original function f (x) by a constant k:
 If 0 <k <1, the function contracts on the y axis
 We have then:
 y = k * (1 / x)
 Where,
 k = 1/3
 y = (1/3) * (1 / x)
 y = 1/3x
 
 the function contracts on the y axis

If it take  some x  minutes to upload  some y  digital photographs, it means it has an average of: x/y minutes to upload a single digital photograph. Then, to upload z photographs, you just multiply   x/y   by z.

Spoilers for
If it take 7.2 minutes to upload 8 digital photographs, it means it has an average of: 7.2/8 = 0.9 minutes to upload a single digital photograph. This means that, by this rate, it will take 20 * 0.9 = 18 minutes to upload 20 photographs to the website.