# math

posted by
**Anonymous** on
.

Express 13/10 - 2/15 as a simplified rational number. I want to make sure I'm doing it correctly. 10 and 15 will go in there 30T and then I said 15 will go in 30 4 T and did I said 10 will go in 30 3T which gave me 35/30 and did I divided it and got 1.16667 do you understand what I just explained.

Not entirely, but I think it's equivalent to this.

What you have are two fractions, so you need to determine a common denominator.

The 2 denominators are 10 and 15. I think you can see that the LCM is 30. If not, run through the multiples of 15 that end with 0.

Thus our expression is equivalent to

(3*13)/(3*10) -(2*2)/(2*15) or,

39/30 - 4/30 = (39-4)/30

You should be able to simplify this. I see that you did get this result. If we divide the top and bottom by 5 we get 7/6, which is approx. equivalent to the decimal you gave.

Do you understand what I just explained?

I'm kinda confuse now well I understand how I got the LCM but once I did that I thought you suppose to times it and then subtract 39 - 4 which is 35/30 then I divided it and I got 1.166667 I don't understand why we're dividing it by 5 can you please explain again for me if you don't mine. Thanks for your help

Yes, we ended up with the fraction 35/30.

The numerator and denominator have a common factor of 5, i.e. (7*5)/(6*5). This is what I meant by dividing the top and bottom by 5.

We simplify the fraction by cancelling the common factors in the numerator and denominator to get 7/6.

This is equivalent to the decimal you got. 7/6 = 1 1/6 ia approx 1.166667.

Does that clarify?