Let's have first a variable representation for each kind.
We let x be the amount of chocolate bars and y be the amount of candies.
For the first hint:
the number of chocolate bars added to twice the number of candies is 33
x + 2y = 33 (1st equation)
For the second hint:
the number of chocolate bars is 6 less than the number of candies
x = y - 6 (2nd equation)
Since we have two equations and two unknowns, then we can solve for x and y
Substitute the 2nd equation to the 1st equation.
x + 2y = 33
(y-6) + 2y = 33
y - 6 + 2y = 33
y + 2y = 33 + 6
3y = 39
y = 13 -the number of candies
Substitute y=13 to the 2nd equation
x = y - 6
x = 13 - 6
x = 7 -the number of chocolate bars
There are 7 chocolate bars and 13 candies.