Adding Algebra

a+a+a+a+a=

(Hint: how many a's?)

b+b+b+b+b+b+b=

(Hint: how many b's?)

x+x+x=

(Hint: how many x's?)

y+y+y+y+y+y+y+y+y+y+y+y+y=

2a+3a=

(Hint: Two a's add three a's...)

4a+2a=

(Hint: Four a's add two a's...)

9a+1a=

(Hint: Four a's add two a's...)

9a+a

(Hint: a just means one a)

1a+2a+3a

(Hint: a just means one a)

 $4x+3x+2x+x=?$