## Sunday, November 4, 2012

### Textbook page 69 #17

17. To calculate - 3/4 + (-2/3), Amy decided to convert the fractions to decimals and add the decimals on a scientific calculator .

A) Explain why she had difficulty in determining the exact answer by this method.

She had difficulty on determining the answer using this method because when you divide 3 by 4 the answer will be 0.75 and when you divide 2 by 3 the answer will be 0.6 repeating now when you add it the answer will be 1.4166666666 which will keep on going making it hard to determine the exact answer because of the repeating number.

B) How should she calculate to get an exact answer.

She should calculate it like this.

First find the common denominator of each fraction in this case it's 12 to make it into equivalent fractions so it's easier to add.
Then you multiply 4 to get to 12 and multiply 3 to get to 12 whatever you do to the top you do to the bottom. Now you add the numerators and the answer is 17/12 or 1 5/12 simplified I think that's how you should calculate it.