Think of it in terms of money. If you've got $5 that's positive. If you owe someone $5 that's negative.
So what's the position if 7 people are each in debt to the tune of $5? $35 in debt in total, so negative 35.
negative
2
It is negative.
37/7
5 is.
It is: 35
105
negative
10
1260
The LCM is 420.
30 - 11 = 19