CD Rom

I have bought a CD rom driver. I have paid $val9 dollars with $val6 CD roms which cost $val7 dollars each. What is the price of the CD rom driver?

Density

The population density of a country is $val6 inhabitants/km². Its population is $val8 millions. What is its area (in thousands of km²)?

Weights

A truck is $val6 times heavier than a car, while the truck is $val7 times lighter than a tank. Knowing that the truck weighs $val8 tons, compute the weights of a car and of a tank (in tons).

Solving Percents using Proportions I

$val6 is $val8 percent of what number (to the nearest hundredth)?

Solving Percents using Proportions II

What is $val8 percent of $val6 (to the nearest hundredth)?

Solving Percents using Proportions III

$val6 is what percent of $val7 (to the nearest hundredth)?

Solving proportions (level 1)

Solve for x:

$val12/x = $val10/$val13

Solving proportions (level 2)

Solve the following proportion.

(enter two solutions)

(x + 1)/x = $val11/(x + $val9)

Solving proportions (level 1c)

Solve for x:

$val13/$val10 = x/$val12

Solving proportions (level 1b)

Solve for x:

$val10/$val13 = $val12/x

Solving proportions (level 1d)

Solve for x: x/$val12 = $val13/$val10