Ben is 20 years older than Daniel. Ben and Daniel first met two years ago. Three years ago, Ben was 3 times as old as Daniel. How old is Daniel now?

The first thing to do is identify the unnecessary information (that they met 2 years ago).  

From there, let's go back three years ago.  We'll call Daniel's age x, and Ben's age will be 3x.  Ben's age is also equal to x + 20.

3x = x+ 20

2x = 20

x = 10

Daniel was 10 three years ago, and Ben was 30.  Now, Ben is 33.

answer

d. 10

explanation

the distance from point y to wx is the height of the triangle.

using pythagoras theorem,

group similar terms to get,

this implies that,

take positive square root of both sides to get,

this implies that,