Question 777836
6* number = 6x
the number's square = x^2
x^2 - 6x = 91
x^2 - 6x - 91 = 0
(x - 13)(x + 6) = 0
x + 6 = 0
x = -6 (no answer as x < 0)
x - 13 = 0
x = 13.
13 is the number.
13^2 - 6(13) = 91
169 - 78 = 91
Hope this helps.
:-)