The radius of a circle is 4 centimeters. What is the area?
r=4 cm
Give the exact answer in simplest form.

Aculture started with 3000 bacteria. after 5 hours it grew to 3900 bacteria. predict how many bacteria will be present after 9 hours

41/17 as a decimal rounded to the nearest hundredth

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of