Two-thirds a number plus 4 is 7

Let the number required be = X
Then the equation is:
(2X/3) + 4 = 7
2X/3 = 7-4
2X/3 = 3
X = (3*3)/2
   = 9/2
Hence the required number is 9/2
Now for checking if the answer is correct we have to backcalculate.
It is given that 2/3 of a number(X) when added to 4 is giving a result of 7
Then
(2/3) * (9/2) + 4
(2*9)/(3*2) + 4
18/6 + 4
3 +4
= 7
So the answer is correct.