Pluto is 5,560,000,000 years old. Estimate the age of Pluto by writing it in the form of x×10y years, where x and y are single-digit numbers.

Imagine a new pasture with grass growing on it. every day after the seeds have germinated, the number of blades of grass in the pasture triples. after 18 days, the entire pasture is completely covered in grass. how many days did it take for the pasture to be one-third covered in grass?

The circumference of a circle is 5 pi cm. what is the area of the circle?

What is (28 + 7 + 6 + 3) x 1/2 show your work