Answer: 5 & 1/8
This is a mixed number.
Whole part = 5
Fractional part = 1/8
This mixed number converts to the improper fraction 41/8
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Work Shown
Method 1
9 - 3 & 7/8
9 - (3 & 7/8)
9 - (3 + 7/8)
9 - (3*8/8 + 7/8)
9 - (24/8 + 7/8)
9 - (24+7)/8
9 - 31/8
9*8/8 - 31/8
72/8 - 31/8
(72 - 31)/8
41/8
(40 + 1)/8
40/8 + 1/8
5 + 1/8
5 & 1/8
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Method 2
9 - 3 & 7/8
(8+1) - (3 & 7/8)
(8 + 8/8) - (3 & 7/8)
(8 & 8/8) - (3 & 7/8)
(8 - 3) & (8/8 - 7/8)
5 & 1/8
Method 2 is much shorter than method 1, but you might find the first method to be easier.
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A real world application.
You start off with 9 pizzas. A bunch of friends stop by and eat 3 whole pizzas, and also 7/8 of a fourth pizza (they don't eat the entire fourth pizza). If you wanted to know how much pizza is left over, then you'd follow method 1 or method 2 shown above to find that there's 5 & 1/8 pizzas remaining.
There's 5 whole pizzas remaining, plus an additional 1/8 of a pizza.