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how do I subtract mixed numbers im confused and I have to do a test on it for tomorrow morning and I need to get my grades u

User Mark Simpson
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1 Answer

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Subtracting mixed numbers.

Let's explain the process to subtract mixed numbers using the following example:


5(1)/(2)-2(3)/(7)

Step 1. Convert each mixed number to a fraction by using the following rule:


A(b)/(c)=((A* c)+b)/(c)

Converting 5 1/2 to a fraction:


5(1)/(2)=((5*2)+1)/(2)

Solving the operations:


\begin{gathered} 5(1)/(2)=(10+1)/(2) \\ 5(1)/(2)=(11)/(2) \end{gathered}

And then we convert the second mixed number 2 3/7 following the same rule:


2(3)/(7)=((2*7)+3)/(7)

Solving the operations:


\begin{gathered} 2(3)/(7)=(14+3)/(7) \\ \\ 2(3)/(7)=(17)/(7) \end{gathered}

Step 2. Now that we have converted the two mixed number to fractions, the original subtraction, which was:


5(1)/(2)-2(3)/(7)

Becomes the following expression by substituting the fractions:


(11)/(2)-(17)/(7)

Step 3. Use the formula for subtracting fractions.

The formula for subtracting fraction is:


(a)/(b)-(c)/(d)=((a* d)-(b* c))/(b* d)

We apply it to our subtraction, in our case a=11, b=2, c=17, and d=7:


(11)/(2)-(17)/(7)=((11*7)-(2*17))/(2*7)

Step 4. Solve the operations to find the result:


(11)/(2)-(17)/(7)=(77-34)/(14)
=(43)/(14)

Step 5. The result of the subtraction in fraction form is:

43/14

But if we need to present it in mixed form, we just find how many times does 14 fits into 43, in this case, 3 times because 14x3=42, so the result in mixed form is 3 as the integer, ans 1/14 as the fraction:


(43)/(14)=3(1)/(14)

User Annelie
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