Question

There are 24 pictures on a roll of film. Adelle had 84 pictures from her trip home. She said that 12 other pictures were spoiled . How many rolls of films did adelle use

Answer 1

The answer is 4.

There were in total 96 pictures (84 pictures  + 12 spoiled = 96 pictures).
1 roll of film has 24 pictures. x rolls of film have 96 pictures.
1 : 24 = x : 96
x = 1 * 96 : 24
x = 4