3/8 unit from 1/2 means you have to add 3/8 to 1/2 to get one of the numbers and subtract 3/8 from 1/2 to get the other number.
If you think of it on the number line, 3/8 from 1/2 is just addition when you move to the right and subtraction when you move to the left.
1) So to subtract fractions, you have to find a common denominator. The common denominator between 1/2 and 3/8 is 8. That means we have to multiply 1/2 by 4/4 (which is equal to 1).

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Now we can find

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One of your numbers is 1/82) To add fractions, we also need a common denominator. We already found the common denominator in part one, so all we need to do is add 3/8 and 4/8 to find your second number:
Your second number is 7/8. Your two numbers are 1/8 and 7/8.