+1222 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?
+37159 (d-7) = (g-7) * 9 Given this can be re-arranged to (d+56) / 9 = g
(d-4) = ( g-4) * 6 Given Solve this system for g sub in the underlined equation (above) for g
d-4 = ( d+56)/9 -4 ) * 6
d-4 = (6d + 336 ) /9 -24
d-4 = 2/3 d + 13 1/3
1/3 d = 17 1/3
d = 52 y/o (and g = 12 y/o)
