Bobby has some marbles.1/3 of them are blue. 1/2 of them are red and the rest are green. If he has 7 green marbles,how many marbles does he have altogether?

Answer 1

If x is the total number of marbles,
(1/3)x + (1/2)x + 7 = x
multiply each term by 6, the LCD, to get rid of fractions and the equation
is easy to solve