these two are fine

now lets think about this. we have 13 and a little bit and we take away 12 and a little bit...how is it we get 26 and a little bit???-12 2/3 + (13 7/8) = 26 13/24

this is also wrong. you did not distribute the minus sign.20 - (-20)= 0

you start with a negative number that is less than negative one and you subtract something from it. the result must be less than negative one also. you can think of it this way if it makes it any easier. factor our the negative sign, we see that -1.6 - 0.8 = -(1.6 + 0.8)-1.6 - 0.8= -0.8

now work that out, and remember the minus sign in front

these are correct5 1/3 - 4 1/2 = 5/6

-25 x 4= -100

incorrect. a negative times a negative is positive-1.2 x (-0.5) = -0.6

these are correct-34 ÷ (-17) = 2

0.456 ÷ -4 = -0.114

5/9 x (-2 2/5) = -1 1/3

-3/5 ÷ 7/10 = -6/7