Perimeter of a Horse Corral Math Challenge

A rancher built a corral for his horses with the dimensions listed above.  What was the perimeter?

Flower Math Challenge

A florist buys roses at $0.50 apiece and sells them for $1.00 apiece.  If there are no other expenses, how many roses must be sold in order to make a profit of $400?  How did you figure that out?

Fun Math Challenge

If you continue the pattern that is shown on the chart below, under which letter would you find the number 100?  Explain how you solved the problem.