Explanation:
360 visitors in 3 hours.
that gives us the ratio
360/3
and because a ratio is nothing else than a fraction with a special meaning, we cab simplify this like any other fraction too :
360/3 = 120/1 = 120
in other words, out of the 3-hour ratio we know that there are 120 visitors in 1 hour.
and now it is easy to use it to find the number of visitors for 7 hours.
remember, if we multiply one part of the fraction by something, we need to multiply also the other part by the same number so that the value of the fraction stays the same.
in other words, we can only do
a/b × c/c
so, if we multiply the bottom part of our ratio by 7 (to go to 7 hours), we also have to multiply the top part by 7 to keep the ratio :
120/1 × 7/7 = 840/7
that tells us that there are 840 visitors in 7 hours.