1) Split the second term in
into two terms.

2) Factor out common terms in the first two terms, then in the last two terms.

3) Factor out the common term 

Answer:
Step-by-step explanation:
the balloon starts at (10, 0 )
it ends at 16,0)
in the middle it's at between 10 and 16 , so say about 13, where it reaches 27
so in the middle it's (13,27)
so ( 11, 9)
(12, 18)
got 13
(14, 18)
(15, 9)
got 16
:P