So add all the numbers together (20 + 22 + 28 + 35 + 47 + 90) and you'll get 242. Then you take the number and divide it by the numbers in your set (you have 6 numbers so you'll divide by 6) 242/6. The answer would be 40.3333333 (repeating decimal). I hope this helps!
First, there was $37.50. Then, there was a tax of 8%. Then, there was a tip of 18%. Since the tip is after the tax, it's not going to affect it, and we can essentially ignore it.
The real question here is just <em>what is 8% of $37.50?</em>
To find the percent of something, first you need to put the percent as a decimal.
8% in decimal form is 0.08 (If you think about it literally, they're both 8 hundredths)
Finally, just multiply the percent in decimal form by the number.