The mean is the average of the numbers. It is easy to calculate: add up all the numbers, then divide by how many numbers there are. 1+1+2+3 +8 = 15 15÷5 = 3
Honestly I can’t remember the last time I had to deal with arcs in school, but the answer to the second one is 63 because all triangles add up to 180 degrees and 46+71= 117. 180-117=63