Hey there!

The unit rate is 8.30 for every hour.
If he earns $8.30 an hour and works 9 hours, multiply 8.30 by 9.
8.30 x 9 = 74.70
Hope this helps!
The circumcenter of a triangle is the point in the plane equidistant from the three vertices of the triangle. so I believe it is A. True..