How do i do 21/2+11/4+45/8?

168 / 16 + 44 / 16 + 90 / 16
302 / 16
151 / 8
18 ⅞

break down the fractions and I think you come out with 18 & 7/8

how can people leave me thumbs down when that is the right answer. dont make much sense.

ok break it down like this. divide the top number by the bottom number. so it looks like this......
21 divided by 2 is 10 .5 or 10 & 1/2
11 divided by 4 is 2.75 or 2 & 3/4
45 divided by 8 is 5.625 or 5 & 5/8
now add them up and get.....
18.875 or 18 & 7/8

use the lcd which in this case is 8
so 21*4 +11*2 +45 = 151/8=18&7/8

151/8

21/2 + 11/4 + 45/8
= (21 x 4)/(2 x 4) + (11 x 2)/(4 x 2) + 45/8
= 84/8 + 22/8 + 45/8
= (84 + 22 + 45)/8
= (106 + 45)/8
= 151/8
= 18 7/8

this is the soution...

change all denominators to 8. I.e. 21/2 = 84/8

depends if you want the answer as a fraction or as a decimal.
Decimal is the easiest. Input it into your calculator like this:
(21/2)+(11*40+(45/8).
Or to find the common denominator, find the lowest number that all of them fit into. THe lowest number they all fit into is 8.
answer like this:
(21/2)*4= 84/8
(11/4)*2= 22/4
(45/8)*1= 45/8
=(45+11+21)/8
=77/8
=9 and 5/8

make sure they all have common denominators