The center of an atom is a nucleus. In the nucleus, there are 2 subatomic particles: protons (positive charge) and neutrons (neutral charge). Outside of the nucleus are electrons. The energy of an electron is in shells. An atom is a single nucleus with a positive charge surrounded by a cloud of negatively charged electrons.[…]

−2x + 3y = −10.5 3x + y = 5 Find the values of x and y.

What is the sum of (6+2i) + (−9+11i) ?

On Monday, Anna starts pouring water into a bucket at a rate of 4 cubic meters per second. Twenty seconds later, Bella starts pouring water into the same bucket at a rate of 5.5 cubic meters per second. How many seconds after Anna starts will the amount of water in the bucket equal or exceed[…]

Sarah drives 55 miles at 60mph. Then she drives for 6 hours at 48mph. Find her average rate.

In a physics problem, rate is inversely related to time for a given distance. When time is 4 hours, rate is 42 miles per hour. Find the rate when time is 6. Now, find the time when rate is 54 mph.