Help Me Please

[BARBARA]

I am new to this program so please bear with me.

I am trying to figure out where I am going wrong with this problem:

1+(4/7-3/4) = 4/7 x 28/28=112/196 - 3/4x28/28=84/196=1+112/196-84/196=1+28/196 = 1 28/196

something don't seem right with this problem. Can someone tell me where i am going wrong?

 

[soroban]

Hello, BARBARA!

I am trying to figure out where I am going wrong with this problem:

1 + (4/7 - 3/4)

. . 4/7 x 28/28 .= .112/196

. . 3/4 x 28/28 .= .84/196 . . . . no

3/4 x 28/28 = 84/112 . . . . . You did not get a common denominator


This is what you wanted:

. . 4/7 x 4/4 .= .16/28

. . 3/4 x 7/7 .= .21/28


Then: .1 + (16/28 - 21/28) .= .1 - 5/28 .= .23/28

 

[wjm11]

I am trying to figure out where I am going wrong with this problem:

1+(4/7-3/4) = 4/7 x 28/28=112/196 - 3/4x28/28=84/196=1+112/196-84/196=1+28/196 = 1 28/196

Consider "3/4x28/28=84/196". How does 4(28) = 196? Obviously it does not, and this is an error. However, what we really need to do is go back and figure out what the LCD means and how to use it. You correctly saw that you had a 4 in one denominator and a 7 in the other. The LCD is the product of these two numbers, 28. That does NOT mean that we multiply each fraction by 28/28. It means we want to multiply each fraction by something that makes the denominator equal 28. So,

(4/4)(4/7) = 16/28

(7/7)(3/4) = 21/28

Now we have two fractions with the same denominator, so we can perform the subtraction:

16/28 - 21/28 = -5/28

Make sense?