Hi,
Let x be the amount of money Bob started with. Then Bessy's amount owuld be 6x
3(x+$6)= (6x + $6)
simplify and Solve
3x + 18 = 6x + 6
12 = 3x
$4 = x
Before earning $6: Bob had 4$ and Bessy $24
After earning $6: Bob had $10 and Bessy $30
checking our answer
3*10 = 30