Question 445412
Mary =x  
John= x/2 (because mary is twice Bob's age)
Bob = 2x ( mary is 1/2 John's age)
After 22 years 
Bob = 2x+22
John = x/2 + 22
2x+22= 2(x/2+22)
2x+22=x+44
2x-x=44-22
x=22 Mary's age