Let the given positive number be xThen x + 42 = x20 = x2 - x - 42or x2 - x - 42 = 0x2 - 7x + 6x - 42 = 0x(x - 7) + 6(x - 7) = 0= (x + 6)(x - 7) = 0x = -6 or x = 7Hence, x = 7