<PRE><B>Question 1184142</B>
&lt;br&gt;
The solution from the other tutor is fine.&lt;br&gt;
Many students might prefer setting up the problem so it can be solved without using fractions....&lt;br&gt;
Given that Peter had 3/8 as many marbles as Simon, let their numbers of marbles by 3x and 8x.&lt;br&gt;
After Simon misplaced 3/4 of his marbles, he had 1/4 of the original number left -- 1/4 of 8x, or 2x.&lt;br&gt;
The number Peter had was now 120 more than Simon had:&lt;br&gt;
3x-2x=120
x=120&lt;br&gt;
The number Peter had was 3x=360.&lt;br&gt;
ANSWER: Peter had 360 marbles&lt;br&gt;
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