+0  
 
0
9
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avatar+1095 

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?

 Aug 6, 2024
 #2
avatar+37101 
+1

(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) 

 Aug 6, 2024

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