In this question, you can get 3 formula which was
1. Paul = Patricia - 2
2. Daniel = Patricia * 1.25
3. Daniel - 10 = (Patricia-10) * 1.5
Daniel - 10 = 1.5 Patricia - 15
Daniel= 1.5 Patricia -5
If you insert the 2nd equation into the 3rd, then you will get
1.25 Patricia = 1.5 Patricia -5
0.25 Patricia = 5
Patricia = 20
Then insert the result into 1st equation
Paul = Patricia - 2= 20-2= 18 years