When three times a number which is postive is subtracted from the square of that

Question

number the answer is 28. Find the number

Answer 1

n^2 - 3 n = 28
n^2 - 3 n - 28 = 0
(n-7)(n+4)= 0
n = 7 for n positive

and yes ----> 49 - 21 = 28 Whew !