Seven years ago, Grogg's dad was $9$ times as old as Grogg. Four years ago, Grogg's dad was $6$ times as old as Grogg. How old is Grogg's dad currently?
grogg's dad's age = D
Grogg's age = G
We can create equations:
(D-7)=9(G-7)
and
(D-4)=6(G-4)
These simplify into
D-7=9G-63
D-4=6G-24
or
D=9G-56
D=6G-20
Because D equals both of these, we know that
9G-56=6G-20
We solve this and get
3G=36
G=12.
We can subsitute this into any of the equations.
6(12)-20 = 52
9(12)-56= 52
So Grogg's dad is 52 years old.
Happy new Year btw :D