In a room a teacher show how to do a math problem.
On a white board is showing the formula for determining interest accrued on money.
A man is writing on a dry erase board and explaining an interest calculation formula.
A person writes an equation on a white surface with a black pen.
A person is using a marker and a whiteboard to solve a difficult  mathematics equation
A calculation of interest on a loan is made with pen an paper with a man explaining in the background.
A man is explaining a math equation on a white board, he is writing the equation at the same time.
A man demonstrates the proper way to do a math equation on a whiteboard.
A man tells how to do a math problem and show how to get the interest on money.
Using a white board and marker, a man demonstrates how to solve a math problem about interest.