Answer:
The speed from the observer is 8 mph.
Step-by-step explanation:
When the boat is going downstream with full force, its speed will be the one the oarsman can row on still water added by the flow of the river. In this case he can row the boat at speed of 3 mph, while the stream is 5 mph, so the speed from the observer standpoint is:

The speed from the observer is 8 mph.
The answer is a enlargement
Answer:
Step-by-step explanation:
The distance formula between two points is d∧2=(x2-x1)∧2 + (y2-y1)∧2
The distance between Vista and Oceanside is
d1∧2=(-1-(-6))∧2+(6-2)∧2=(-1+6)∧2+4∧2=5∧2+16=25+16=41 => d=√41= 6.4
The distance between Oceanside and Alpena is
d2∧2=(0-(-1))∧2+(-1-6)∧2=1+(-7)∧2=1+49=50 => d2=√50=7.07
The distance between Vista and Alpena is
d3∧2=(0-(-6))∧2+(-1-2)∧2=36+9=45 => d3=√45= 6.7
Answer a) is Oceanside and Alpena
Answer b) is Vista and Oceanside
Good luck!!!