Lost His Marbles
Livingston is a marble freak and loves to play at school. During the first break, he doubled the number of marbles he had. During the second break, he lost four marbles (no big deal). During the third break, he increased his stock of marbles by 1/3. During lunch, however, he lost half of his marbles. After school, Livingston played again and tripled what he had. He went home with 72 marbles. How many did he start with?
The answer is 20.
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1 solution
let x be the total no. of marbles Livingston started with
After first break Livingston has 2x. After second break he has 2x-4. After third break he has (2x-4) +(1/3)(2x-4)=(8x-16)/3. After lunch he has (4x-8)/3. After school he has 3(4x-8)/3=4x-8. At home he has 4x-8=72 i.e x=20.