Solve the following proportions:
h) Knowing that x + y = 42, determine x and y in proportion .
i) Knowing that a + b = 55, determine a and b in proportion .
j) The sum of the age of the father and son is 45 years. The age of the father is to the age of the child, just as 7 is to 2. Determine the age of the father and son.