What is the area of a regular decagon if the length of each side is 20 units?

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.

Look at the chart showing the results of a baseball player at bat. which is the probability of getting a hit?