The constant of proportionality.

Two are defective.

None is defective.

How many 3-digit numbers greater than 300 can be made out from digits 0, 1, 2, 3, 4, 5, and 6 if repetition of digit is not allowed?

In a class experiment, a student needs 5 liters of 6% solution. He found a 4% and a 10% solution in the laboratory. How many liters of each solution should he mix in order to obtain 5 liters of 6% solution?

The distance between the centers of the three circles which are mutually tangent to each other externally are 10, 12, and 14 units. The area of the smallest circle is:

Express the following statement mathematically: 5 less than four times a certain number is 12.

Determine the value of a if (x + 2) is a factor of (x³ - ax² + 7x + 10).

Find k so that the expression kx^2 - 3kx + 9 is a perfect square.