Question 87278
first define ages:
Let x = john's age NOW
Let y = mery's age NOW


so: john is 12 years younger than mery  --> x=y-12
--> y = x+12

and: mery's age in 8 years will exceeed twice john's age 3 year's ago by 4 years --> y+8 is Mery's age in 8 years time. John's age 3 years ago was x-3. So,
y+8 = 2(x-3) + 4
--> y+8 = 2x-6 + 4
y+8 = 2x-2
y = 2x-10


So we know that y= both of the Right hand terms so those 2 right hand terms must be the same number:


x+12 = 2x - 10
12 = x - 10
22 = x


if x=22
then y = x+12
--> y = 22+12
--> y = 34


You try the other one


cheers
Jon