Most of the information's necessary for solving this problem is already given in the question.
Let us assume the number to be = x
Then
25% * x = 19
(25/100) * x = 19
x/4 = 19
x = 19 * 4
= 76
So the unknown number is 76. I hope there is no complexity in the method described above and also the procedure is clear enough for you to understand. You can use this method for solving similar type of problems in future without requiring any additional help from outside.