Tori had 5/7 fossils as Tommy. Tommy gave 6 fossils to Tori so that they would each have the same amount .How many fossils did the two friends have altogether?

Tommy's number --- x

Tori's number = (5/7)x

after give away:
Tommy has x-6
Tori has (5/7)x + 6

now the numbers are equal, so
x-6 = (5/7)x + 6
times 7
7x - 42 = 5x + 42
2x = 84
x = 42

take over