Answer:
60 miles per hour southeast.
Step-by-step explanation:
We are told that the car is moving southeasternly, so that answers the question right off the bat. The car is moving 120 miles per 2 hours. We need to know how much it moves in one hour though, so we must divide hours and miles by 2. We ger 60 miles per hour.
Step 
In the right triangle ADB
<u>Find the length of the segment AB</u>
Applying the Pythagorean Theorem

we have

substitute the values



Step 
In the right triangle ADB
<u>Find the cosine of the angle BAD</u>
we know that

Step 
In the right triangle ABC
<u>Find the length of the segment AC</u>
we know that




solve for AC

Step 
<u>Find the length of the segment DC</u>
we know that

we have


substitute the values


Step 
<u>Find the length of the segment BC</u>
In the right triangle BDC
Applying the Pythagorean Theorem

we have

substitute the values



therefore
<u>the answer is</u>

Answer:
Speed of river's current = 5 mph
Step-by-step explanation:
Let 'd' be the distance covered
Let x be the speed of the rivers current
Speed upstream = 15-x
speed downstream = 15+x
Time = distance / speed
time upstream = 
time downstream = 
the ferry trip upstream takes twice as long as its return trip downstream
= 
divide both sides by d
= 
cross multiply


Add 2x on both sideds

subtract 15 from both sides and divide by 3

x=5
Speed of river's current = 5 mph
There are 100 tens in 1,000