The number is 6860
The number 6 goes in both boxes
Answer:

Step-by-step explanation:

Answer:
3 Blue Umbrellas
Step-by-step explanation:
Given



From the question, we have:
---- i.e. 6 are not blue
---- i.e. 6 are not yellow
---- i.e. 6 are not red
Required
The number of blue umbrellas
Make B the subject in: 

Substitute:
in 

Collect like terms


Rewrite:

Substitute
in 


Divide both sides by 2

Recall that: 


I think it’s 3 because it’s just how I think it is I’m probably not correct but I think it’s 3