divide distance by speed
equation: time = distance / speed
120/8.5 = 14.117 seconds
We must find UNIQUE combinations because choosing a,b,c,d... is the same as d,c,b,a...etc. For this type of problem you use the "n choose k" formula...
n!/(k!(n-k)!), n=total number of choices available, k=number of choices made..
In this case:
20!/(10!(20-10)!)
20!/(10!*10!)
184756
Parallelogram: opposite angles are equal ; opposite sides are equal
<JML = <LKJ and <MJK = <MLK
Answer is the second option (opposite angles are equal)
<JML = <LKJ and <MJK = <MLK