Question 1184677
If Gordan had x marbles at the start, then Harry had 340 - x marbles initially.


After Gordan gave away 2/5 of his marbles, he would have {{{(3x)/5}}} remaining.  Harry gave away 20 of his marbles, so he has 320 - x afterwards.


Then from the given, {{{(3x)/5 = 320 - x}}} ===> x = 200, the number of marbles Gordan had at the beginning.  ===> Harry had 140 marbles at the beginning. 


===> Harry had 120 marbles in the end.