ADDING A MIXED NUMBER FRACTION

what is 2 3/10 - 7 3/20? Is the answer -5 3/20? Thats what I got, am I right?

You're on the right track I think. There's two ways two solve this problem. You could convert each mixed number to an improper fraction and then add them, or you can add the whole numbers and then the fractions.

Here goes:

2 3/10 - 7 3/20

I will convert them to improper fractions.
2 3/10 = 23/10
7 3/20 = 143/20

Now we want a common denominator:
23/10 = 46/20

Now subtract the fractions:
46/20 - 143/20 = -97/20

Finally convert back to a mixed number:
-4 17/20


Your answer was close, and I think I know what you did. You probably subtracted the two whole numbers (2 - 7 = -5) and then the fractions (3/10 - 3/20 = 3/20). However, you have to remember that you are adding that fraction back on. When you say -5 3/20 that means negative five and 3/20ths, which means the 3/20ths is really negative as well, because it makes the whole thing more negative.

In other words, the number is really -(5 3/20) which makes it clear that you subtracted the 3/20 when in fact it should have been added.

The point of all that is that you got the -5 correctly and the 3/20 correctly, but you have to remember to add them: -5 + 3/20 = -4 17/20

I know that wasn't very clear... do you understand what I am saying?

thanks and a couple more questions!

Thanks Ted!! I understand now...I have another question:

for converting decimals to fractions or mixed numbers, would this be right:

0.426

0.426/1000 = 426/1000 (divided by 2) = 213/500??

Also for adding these fractions:
19/30 - 22/75= 95/150- 44/150= 51/150??

sorry but I have another!

(-2 1/8) (-5 1/7)= -10 52/56??

Correct.

Correct.

So close... you did the arithmetic right but its a negative times a negative so the answer is a positive.