Three non negative numbers A, B and C are such that the mean is X and the median is 7. If X is 12 more than the smallest number and 17 less than the biggest number. Find the value of A + B + C.
Give positive numbers a, b and c are such that ab + bc + ca + abc = 4, What is the value of 1/a+2 + 1/b+2 + 1/c+2 = ?