Question 265690
My granddaughter is as many days old as my daughter is weeks.
 My granddaughter is also as many months old as I am years.
 My granddaughter, my daughter and i have a combined age of 120 years.
 How old am I?
:
Let
 d = age of granddaughter in days
 d = age of daughter in weeks
From this we can say daughter is 7 times as old as granddaughter
:
 m = age of granddaughter in months
7m = age of daughter in months
 m = age of myself in years
:
change gr-daught and daugt ages from months to years, divide by 12
:
{{{m/12 + (7m)/12 + m}}} = 120
Multiply equation by 12
:
m + 7m + 12m = 12(120)
20m = 1440
m = 1440/20
m = 72 is my age
:
72/12 = 6 yrs is granddaughter
7(72)/12 = 42 yrs is daughter
:
Total: 6 + 42 + 72 = 120