Livingstone is a marble freak and loves to paly at school. During the first break, he doubled the number of marbles he had. During the second break, he lost 4 marbles. During the third break, he increased his stock of marbles by one-third. 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 much did he start with? work backword to answer this question. Solution consider he had x marblles During the first break, he doubled the number of marbles he had. = 2x During the second break, he lost 4 marbles =2x-4 During the third break, he increased his stock of marbles by one-third =2x-4 +1/3 (2x-4) During lunch, however, he lost half of his marbles. = (2x-4 +1/3 (2x-4))/2 After school, livingston played again and tripled what he had = 3(2x-4 +1/3 (2x-4))/2 He went home with 72 marbles 3(2x-4 +1/3 (2x-4))/2 = 72 (3/2)(4/3)(2x-4) = 72 4x-8 =72 4x = 80 x=20 he start with 20 marbles.

1. Livingstone is a marble freak and loves to paly at school. During the first break, he doubled the
number of marbles he had. During the second break, he lost 4 marbles. During the third break, he
increased his stock of marbles by one-third. 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 much did he start with? work backword to answer this question.
Solution
consider he had x marblles
During the first break, he doubled the number of marbles he had. = 2x
During the second break, he lost 4 marbles =2x-4
During the third break, he increased his stock of marbles by one-third =2x-4 +1/3 (2x-4)
During lunch, however, he lost half of his marbles. = (2x-4 +1/3 (2x-4))/2
After school, livingston played again and tripled what he had = 3(2x-4 +1/3 (2x-4))/2
He went home with 72 marbles
3(2x-4 +1/3 (2x-4))/2 = 72
(3/2)(4/3)(2x-4) = 72
4x-8 =72
4x = 80
x=20
he start with 20 marbles