Posted by Suzanne on .
Hello, I need did a subtraction problem with mixed numbers by converting the LCD of the denominator.
However, when I went to Algebra.help they did the problem by converting the mixed problem to an improper fraction and then worked it that way.
However, I know that the answers should be the same.
Please check my method. I don't want to convert the whole numbers to mixed.
9 10/12 minus 5 6/7
9 70/84 minus 5 72/84
equals 4 2/84
reduced to 4 1/42
Algebra help say the answer is:
3 41/42

methods of sbtracting mixed fractions 
Ms. Sue,
Your algebra help is correct.
Your problem is in your second step. You can't take 72 from 70. Therefore, you need to change 9 70/84 to 8 154/84.
8 154/84  5 72/84 = 3 82/84 = 3 41/42 
methods of sbtracting mixed fractions 
Suzanne,
How did you change 9 70/84 to 8 154/84?

methods of sbtracting mixed fractions 
Ms. Sue,
Subtract 1 frp, 9 and add to the fraction.
1 = 84/84 
methods of sbtracting mixed fractions 
Nat,
23/6 convert to a mix number