Solution :
Give that a shark can chase prey about 30 miles per hour.
1 hour = 60 minute
by using unitary method, we will convert miles per hour into miles per minute
in 60 minutes the shark can chase the prey 30 miles
In 1 minute the shark can chase 
Hence the shark can chase the prey about 0.5 miles per minute.
Each of 4 friends has 2 balloons
4 x 2 = 8
herself has one
so 8 + 1 = 9
answer: Total 9 balloons
D=2x+2
X=7
Plug in the value for Max's age.
D=2(7)+2
D=14+2
D=16
Max is 7
Dee is 16