If 3a+4a=14, and b+6b=21, then 7(a+b) =Help and show work!

Hello!

You have to find what a and b are

3a + 4a = 14
b + 6b = 21

Lets do a first

3a + 4a = 14

Combine like terms

7a = 14

Divide both sides by 7

a = 2

Now lets do b

b + 6b = 21

Combine like terms

7b = 21

Divide both sides by 7

b = 3

Put a and b into the third equation

7( 2 + 3) = 

Do what is in parenthesis first

7(5) = 

Multiply

35

The answer is 35

Hope this helps!