Question 348574
6 years ago 
joan x
jun 4x
..
after 4 years
joan x+10
Jun  4x+10
4x+10=2(x+10)
4x+10=2x+20
4x-2x=20-10
2x=10
x=5  joan 6 years ago. Now age = 11
Jun 4x, = 20, 6 years ago. Now age =26 years now
.......
Let pedro's age be x  ( pedro's age is 1/4 of father'e age OR father is 4 times pedros age)
father's age = 4x
..
20 years later
pedro = x+20
Father = 4x+20
2(x+20)=4x+20
2x+40 =4x+20
2x=20
x=10 pedro's age now
father= 10*4 = 40 years