John gave ¹₈ of his marbles to Brandon, ¹₉ of his remaining marbles to Carl and ¹₇ of the rest of his marbles to Peter. He then had 192 marbles left. How many marbles had he at first?
Fraction of the rest of the marbles that John had left after giving to Brandon, Carl and Peter
= 1 - ¹₇
= ⁶₇

⁶₇ of the rest of the marbles that John had left = 192
¹₇ of the rest of the marbles that John had left = 192 ÷ 6 = 32
⁷₇ of the rest of the marbles that John had left = 7 x 32 = 224

Fraction of his remaining marbles that John had left after giving to Brandon and Carl
= 1 - ¹₉
= ⁸₉

⁸₉ of his remaining marbles that John had left = 224
¹₉ of his remaining marbles that John had left = 224 ÷ 8 = 28
⁹₉ of his remaining marbles that John had left = 9 x 28 = 252

Fraction of his remaining marbles that John had left after giving to Brandon
= 1 - ¹₈
= ⁷₈

⁷₈ of the marbles that John had left = 252
¹₈ of the marbles that John had left = 252 ÷ 7 = 36
⁸₈ of the marbles that John had left = 8 x 36 = 288

Number of marbles that John had at first = 288

Answer(s): 288