Respuesta :

Answer:

19

Step-by-step explanation:

it is 19 because, if you have 10 marbles, and then your friend has 9 and gives it to you, then you go from 10 then 11 then 12 then 13 then 14 then 15 then 16 then 17 then 18 then 19.

nobody5678900

Answer:

21

Step-by-step explanation:

9 = 3 x 3

10 = 5 x 2

3 x 2 = 6

3 x 5 = 15

15 + 6 =21