Two mountain bikers take off from the same place at the same time. one travels north at 4 mph, and the other travels east at 3 mph. how far apart are they after 4 hours? a. 14 miles b. 20 miles c. 28 miles d. 5 miles

20 miles (Answer B)

Step-by-step explanation:

The northbound biker travels (4 mph)(4 hr) = 16 mi, and

the eastbound biker travels (3 mph)(4 hr) = 12 mi.

They travel at right angles to one another.  Thus, the Pythagorean Theorem applies here.  The distance between the two bikers is d = √( [12 mi]^2 + [16 mi]^2 ), or √(144 + 256) mi, or √400 mi, which works out to 20 miles.

Answer B is correct.

Remember that negative times positive=negative

conver to improper
4 and 1/2=4+1/2=8/2+1/2=9/2
2 and 1/2=2+1/2=4/2+1/2=5/2

-4 and 1/2 times 2 and 1/2=
(-9/2) times (5/2)=
-(9*5)/(2*2)=
-45/4=
-44/4-1/4=
-10-1/4=
-10 and 1/4