The length of a rectangle is twice its width. If its perimeter is 54 cm, find its length.

A rectangle's length is 5 cm less than twice its width. If the length is decreased by 5 cm and width is increased by 2 cm, the perimeter of the resulting rectangle will be 74 cm. Find the length and the width of the original rectangle.

A man's age is three times that of his son and in twelve years he will be twice as old as his son would be. What are their present ages?

A man is 42 years old and his son is 12 years old. In how many years will the age of the son be half the age of the man at that time?