Answer & Explanation
Present
Deepak: D + 7
Samir: 3D + 7
4 years from now
D's age: D+11
S's age: 2(D+11)
Now we just need to represent this with an equation. What is one more piece of information that we know that isn't represented by this table? Well, we know that people age at the same rate. So Samir's age 4 years from now will be 11 more than his age was 7 years ago. So we can write:
3D + 11 = 2(D + 11)
And then we can solve for D:
3D + 11 = 2(D + 11)
3D + 11 = 2D + 22
D + 11 = 22
D = 11
Then, remember that D = Deepak's age 7 years ago.
So that means 11 + 7 = 18, his age now.