857 runners entered a race. 354 more entered before the race started. How many runners are in the race?

Me. i can't figure out this question. give an explanation too. .

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.

Aparking garage charges $1.12 for the first hour and 0.50 for each additional hour. what is the maximum length of time tom can park in the garage if we wishes to play no more than $5.62