Question 1172522
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I personally would do a little work with the given information to set up the problem without the need to work with decimals.<br>
Since 80% is 4/5, let the original numbers of marbles be 4x for Mac and 5x for Jack.<br>
Then, after Mac gives 48 marbles to Jack, the numbers are 4x-48 and 5x+48.<br>
At that point, the number of Mac's marbles is half the number of Jack's:<br>
{{{4x-48 = (1/2)(5x+48)}}}
{{{8x-96 = 5x+48}}}
{{{3x = 144}}}
{{{x = 48}}}<br>
ANSWER: The number of marbles Jack started with was 4x = 4(48) = 192.<br>