Question

Can you check my answers:
2) 5/8 - 1/4
i got: 3/8

4) 1 1/2 - 2 4/5
i got: 7/10

6) 5 7/8 + 3 5/12
i got: 9 7/24

10) 3 1/2 + 2 2/5
i got: 5 9/10

18) 6 7/12 + 4 5/12
i got: 11

20) 7 9/10 + 3 3/10
i got: 11 1/5

22) 18 3/8 + 11 6/7
i got: 30 13/56

24) 26 9/10 + 72 5/6
i got: 99 11/15

26) 3/14 + 17/63
i got: 61/126

28) 2 5/6 - 2 5/22
i got: 20/33

30) 3 5/9 - 2 11/12
i got: 23/36

are these right?

Answer 1

all correct except #4
1 1/2 - 2 4/5
= 3/2 - 14/5
= 15/10 - 28/10
= -13/10 or -1 3/10

If you have a scientific calculator with a key labeled
a b/c , you can perform calculations in fraction form
It will do the required operation such as addition by taking care of finding lowest common denominators etc.
It does of course not show any in-between steps.
e.g. to do 1/2 + 2/3
press:
1
a b/c
2 +
2
a b/c
3
=
to get 1 1/6
if at this point you press
2ndF
a b/c
you will get 7/6 , the improper function

to enter a mixed number like 5 3/4
press:
5
a b/c
3
a b/c
4

Use it only to check your answer, since your teacher will probably insist that you show all steps.