ARG!!! I dont get this math problem!!!?

Question

In a nation of 221 million people, the urban population is 2.25 times the rural population. Find the rural and the urban populations. (plz explain in detail...)

do you get this one too?
A dealer buys a new car for 8400. how much do you have to pay for the car if the dealer makes a 20% profit and there is a 5% sales tax?

Answer 1

Let U be the urban population and R be the rural.

Then U+R = 221 million
U = 2.25 * R

2.25 * R + R = 221 million.

You should be able to take it from there!

Answer 2

It is a simultaneous solution problem, which is where you need to get two equations and substitute one into the other.

In this case, let U be the urban population and R be the rural population. We know that the urban population is 2.25 times bigger than the rural population, and we can express this as:

U = 2.25 * R

We also know that the rural and urban populations must add up to 225 million:

U + R = 221 million

But we know from the first equation that U = 2.25R, so we can substitute that in to the second equation:

2.25R + R = 221 million

Which is the same as saying:

3.25R = 221 million.

Divide both sides by 3.25, and you get:

R = 68 million.

Now that you know R, you can work out U from the first equation above.

Answer 3

I will use r for the rural population.
The urban population is 2.25 times x or 2.25x
The total population is 221 which is composed of rural and urban so the equation is:
2.25x + x = 221
3.25x = 221
x = 68 The rural population is 68 million
2.25(68) = 153 The urban population is 153 million
68+153 = 221 The total population

I hope this helps

Answer 4

Rural Population is 68 million
Urban population is 153 million

Answer 5

u+r=221,000,000 total population of 221,000,000
u=2.25r urban population is 2.25 times the rural population

substitute 2.25r for u in the 1st equation
2.25r+r=221,000,000
3.25r=221,000,000, divide both sides by 3.25
r=68,000,000 rural population
u=2.25r=2.25*68,000,000
u=153,000,000 urban population.