Answer:
878
Step-by-step explanation:
439 x 2
2x9= 18
2x30=60
2x400=800
Then add
800+60+18
60+18=78
800+78= 878
15
15÷3=5
15 is between 10 and 20
64/81
The drawing will help
55
(after the first "1") You need to add the previous two numbers together to get the next number in the pattern.
& 