Answer:
10 kph
Step-by-step explanation:
Find the speed of the current of the river.
20/(20 - c) + 180/(20 + c) = 8
20(20 + c) + 180(20 - c) = 8(400 - c^2)
8c^2 - 160c + 800 = 0
8(c^2 - 20c + 100) = 0
8(c - 10)^2 = 0
c = 10
The speed of the current of the river is 10 km/hour.
First, take a look at 3 less than twice x. Twice x would be 2x and 3 less than it would become 2x-3.
Next, 2 more than the quantity 3 times x. The quantity of 3 times x is 3x and 2 more than that would be 3x+2.
Now that we have our two equations, we need to multiply them together, which can be shown as (2x-3)(3x+2).
Then, multiply the two equations together using FOIL (multiply the first two terms, then the outside terms, then inside, and lastly, the last two terms): 2x times 3x, 2x times 2, -3x times 3x, and 2 times -3, which equates to 6x^2+4x-9x-6.
Your final answer is 6x^2-5x-6.
Answer:
x = 15/4, - 4
Step-by-step explanation:
I'm not sure :p
First add the prices of the original books.
2.5+4.95+6=11.45
Find 20% of 11.45
=2.29
Therefore I saved $2.29
