Question 853824
Let pat present age be x.
Then gray present age is 2x. 
20 years ago,
pat age=x-20
gray age=6(2x-20)
then we get,
2x / x = 6(2x-20) / x-20
2(x-20) = 6(2x-20)
2x - 40=12x - 120
12x - 2x = 120 - 40
10x = 80
x = 8 years and 
gray present age =2x=16 years