Theresa has an umbrella stand at the beach. - All of them are blue, except for six. - All of them are yellow, except for six. - All of them are red, except for six. How many blue umbrellas does Theresa have?

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:

step-by-step explanation:

first, eliminate the parenthesis:

3

x

+

2

−

4

x

second, group like terms:

3

x

−

4

x

+

2

third, combine like terms:

(

3

−

4

)

x

+

2

→

−

1

x

+

2

→

−

x

+

2