Find Their Current Age

[nycmath]

Bruce is 4 years younger than Hector. Twenty years ago, Hector’s age was 13 years more than half the age of Bruce. How old are they now?

[Eigenvalue]

Let B be Bruce's age and H be Hector's age

B=H-4
H-20=0.5(B+20)+13
H=B+4
H-20=0.5B+23
B-16=0.5B+23
0.5B=39
B=78
H=82