Dan is watching the birds in his backyard he watches none of them or 45% are sparrows how many birds are in his backyard

If 9 of the sparrows is 45% of the birds in the backyard, 9/x = 45/100.

Cross multiply to get 9 * 100 = 45x; simplified is 900 = 45x or 20.

This means that there are 20 birds in the backyard. You can check this by dividing 9/20 which equals 45%

none??' you mean nine?

so, converting firstly the mixed fractions to improper fractions and then "adding".

nope.   happens to me as well.

-aparri