Please help solve Problem of the Week

Waiting in line...

The week before the big concert, five friends Alan, Ben, Cameron, Derryck, and Garrett, stood in line to buy tickets. There were other people there, but the five friends were in the line in the order listed above. The line was really long, and they were pretty bored. Cameron noticed that if he counted the number of strangers between each pair of friendss, he got the numbers 7,12,19,21,36,43,55,57,64,76. Like i said, he was REALLY bored! he sent this info. to Garrettin a paper airplane, and he passed the time in line using Camerons info. to determine how many people were between Alan and Ben , Ben and Cameron, Cameron and Derryck, and between Derryck and Garrett. How many people are between:
A&B____ B&C____ C&D____ D&G_____?

GCF