A pebble drops from a balcony that is 80 feet above the ground. The pebble lands on the top of a sign that is 16 feet high. The function y=80−16t2 represents the height y (in feet) of the pebble t seconds after dropping from the balcony. How many seconds does the pebble drop before hitting the sign? The pebble hits the sign after seconds.

t =2 seconds

Step-by-step explanation:

We have, a function that represents the height y of the pebble after dropping the balcony as follows :

The pebble lands on the top of a sign that is 16 feet high.

It is required to find the time does the pebble drop before hitting the sign. The above equation becomes,

So, the pebble hits the sign after 2 seconds.

he spend 5.1 minutes chatting with his friends.

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5.1

  or  

step-by-step explanation:

if the four friends split the cost, p, of the pizza evenly, then each friend pays one-fourth of the cost of the pizza.

the expression is   or