Answer:
9 mph
Step-by-step explanation:
-let x be the speed of current and t be time. The speed equation for both directions can then be represented as:

#Since t is equal in both, we can do away with t.
#We the divide the downstream equation by the upstream equation as:

Hence, the boat's speed in still water is 9 mph
Answer:
30 ways
Step-by-step explanation:
The first medal can be awarded in 6 different ways since any of the runners could have it. Once the first medal is awarded, the second medal can only be given to any of the 5 runners available.
So there are 6x5=30 different ways to award the medals
Answer:
Step-by-step explanation:
Parallel lines have the same slope. The slope of the given line is 3. The easy way to do this, the one that uses our logical brains as opposed to our mathematical brain, tells us that since there is only one choice that has a given slope of 3, that is the one that we want. The second choice down is the only one that has a slope of 3.
Mathematically,
and
and
so
y = 3x - 7 (the second choice)