it seems like you have the answer already. but heres how its calculated.
[tex] \frac{100}{15} = \frac{?}{3} [/tex]
so the missing number is 20 **cross multiply 100 and 3 to get 300 then divide 15 into 300 to get 20**
[tex] \frac{160}{100} = \frac{80}{?} [/tex]
so the missing number is 50
**cross multiply 100 and 80 to get 8000 then divide 160 into 8000 to get 50**