Question 832350
Let Ann's age be "x", and Chuck's age be "y"
We have she's three year older than chuck, meaning we have the equation
x = y + 3 
x - y = 3
Then we have in five years, the total of both will be 54
Notice this, in five years, that mean you have to add 5 to both variables
(x+5) + (y+5) = 54 
x + y + 10 = 54
x+y = 44
So now we have two different equations, let's combine them and solve the system of equations
*[invoke linear_substitution "x", "y", 1, -1, 3, 1, 1, 44 ]
Well, the answer is kind of odd but I'm pretty sure that I did it right, so if you find any mistake you can leave a comment and I would be happy to look at it 
:D