If [tex]b[/tex] is Ben's age and [tex]i[/tex] is Ishaan's age, then
- present day: [tex]b=4i[/tex]
- 6 years ago: [tex]b-6=6(i-6)[/tex]
Rewrite the second equation as
[tex]b-6=6(i-6)\implies b-6=6i-36\implies b+30=6i[/tex]
Substitute [tex]b=4i[/tex] into this equation to solve for [tex]i[/tex]:
[tex]b+30=6i\implies4i+30=6i\implies30=2i\implies i=15[/tex]
Then
[tex]b=4i\implies b=4\cdot15=60[/tex]
So Ben is 60 years old now.
