Question 174820
Let x = Adam's current age
Let y = Eve's current age

So currently, x = y-5
In one year, y+1=3*(x-4)

Rearranging the equations we have

-y+x=-5
y-3*x=-1-12=-13

So the two equations are

-y+x=-5     (Equation #1)
y-3*x=-13  (Equation #2)

Add the two equations to eliminate "y"

-y+y+x-3*x=-5-13

-2*x = -18

Therefore, x = 9

Substituting x = 9 into equation #2

y -3*x = -13 (Solve for y)
y -3*9 = -13      Set x = 9
y -27 = -13
Therefore, y=14

Using the graphical method as a check

{{{graph(300,300,-5,20,-5,20,x+5,3*x-13)}}}