Question

Kevin is 3 times as old as Daniel. 4 years ago, Kevin was 5 times as old as Daniel.

Answer 1

X is Kevin; Y is Dan

X = 3Y

X - 4 = 5(Y - 4)


3Y - 4 = 5(Y - 4)   
3Y - 4 = 5Y - 20
     + 4         +4
4 cancels each other out.
     3Y = 5Y - 16
     - 5   -5
5 cancels each other out.
    -2Y = -16  
    /2       /2     
       Y = 8 

X = 3Y;    
X = 3 x 8;

Thus,
X = 24;
Kevin(x) is 24