Question

please answer this question very fast and and step by step and full explanation and don't write the wastage answer and please help me for the correct answer experts please .....

Answer 1

Let the number to be added be x.
According to the question,
(1+x)/(4+x) = (7+x)/(11+x)
(1+x)(11+x) = (4+x)(7+x)
11 + x + 11x + x^2 = 28 + 4x + 7x + x^2
12x-11x = 28 -11
x = 17
Hope it helps.