A number is first decreased by one-fifth of its value and then increased by one-fourth of the resulting value. If the final result is 48, what was the original number?

A fraction is equivalent to 0.375. If 5 is added to its numerator and 8 to its denominator, the resulting fraction is 1/2. What is the original fraction?

If a - b = 4 and ab = 12, what is the value of a² + b²?

Suppose n is an integer such that the sum of the digits of n is 2, and 10¹⁰ <n < 10¹¹, The number of different values for n is

If a, b, c, d, e and f satisfy 2a = 3b = 6c = 9d = 12e = 18f, then what is the value of (a + b)/(c + d + e + f)?

If you subtract 1/2 from a number and multiply the result by 1/2, you get 1/8. The number is