Bummer! Kai lives in California and of course he has to pay sales tax! The sales tax rate is 8.75%. Now, does
he have enough money to bring the backpack of his
dream home?
(Original price: $88.95, 40% off and Kai has $55.00
saved up so far.)

actually what is a question i don't understand

answer: 4  

the square root of 16 is 4. it is a very simple mathematic concept. a square root when a number multiplied by itself will result in a number. here, the number 16 comes when 4 is multiplied by 4. hence the square root of 16 is 4. you can always figure out a square root by the inverse operation of squaring.  

the distance between the school and her home is 3.6km.

12 mins = 0.2 hours = 1/5 hour

54 ÷ 3 = 18km per hour

1/5 of 18 = 3.6km per 12 mins