Speed = Distance / Time
Distance = Speed*Time
For this problem, we should bear in mind that current speed has an impact on the boat speed...
for upstream, the boat goes against the current, and so its speed is
U = V - C
where V is the speed of the boat
C is the current speed
for downstream, it will be:
D = V + C
Convert the problem into mathematical equations:
4D + 3U = 116
3D + 4U = 108
4(V+C) + 3(V-C) = 116
4V + 4C + 3V -3C =116
7V + C = 116
3(V+C) + 4(V-C) = 108
3V + 3C + 4V - 4C = 108
7V - C = 108
Solving the equations:
7V + C = 116
7V - C = 108
14V = 224
V = 16km/hr —-> speed of boat
to get C:
7(16) + C = 116
C = 4km/hr
Answer:
90 hardcover books
Step-by-step explanation:
We can solve this by setting up a couple of equations.
Let's allow x to represent the number of paperbacks Tim owns, and allow y to represent the number of hardcover books he owns.
Using the information in the question, we can write the equations:
1)x = 4y-3
2) x+y=447
Let's rearrange equation 1 so that it is in standard form:
x-4y=-3
And then let's multiply equation 2 by 4 so that we can cancel out y when we solve the system of equations:
4(x+y=447)
4x+4y=1,788
Then we can add the two equations and solve for x:
1) x-4y=-3
+ 2)4x+4y=1,788
------------------------------------
5x=1,785
x=357
So now we now the number of paperback books Tim has is 357. Let's plug this into one of the original equations to solve for the number of hardcover books (y):
357+y=447
y=90
And now we know that Tim owns 90 hardcover books.
24.045
is the answer
5% of 22.90 is 1.145
1.145*22.90
