3 chocolate bars and 4 packets of candy weigh 200 g. 3 chocolate bars and 7 packets of candy weigh 260 g. What is the weight of a chocolate bar?

4P = 200 - 3C

3C + 7P = 260

3C + 7*(200-3C)/4 = 260

Solve for C.

x = weight of a chocolate bar

y = weight of a candy bar

Solve system of equations:

3 x + 7 y = 260
-
3 x + 4 y = 200
____________

3 y = 60

y = 60 / 3 = 20 g

3 x + 4 y = 200

3 x + 4 ∙ 20 = 200

3 x + 80 = 200

3 x = 200 - 80

3 x = 120

x = 120 / 3 = 40

The weight of a chocolate bar = 40 g

To solve this problem, we can use a system of equations. Let's represent the weight of a chocolate bar as 'c' and the weight of a packet of candy as 'p'.

According to the information given:
3c + 4p = 200g (Equation 1)
3c + 7p = 260g (Equation 2)

We have two equations with two unknowns.

First, let's eliminate 'c' by subtracting Equation 1 from Equation 2:
(3c + 7p) - (3c + 4p) = 260g - 200g
3p = 60g

Now we can solve for 'p' by dividing both sides of the equation by 3:
p = 60g / 3
p = 20g

So, the weight of a packet of candy is 20 grams.

To find the weight of a chocolate bar, we can substitute the value of 'p' in either of the original equations. Let's use Equation 1:
3c + 4(20g) = 200g
3c + 80g = 200g
3c = 200g - 80g
3c = 120g

Now divide both sides of the equation by 3 to solve for 'c':
c = 120g / 3
c = 40g

Therefore, the weight of a chocolate bar is 40 grams.