Four classes are collecting recyclable paper for a school challenge. The bar graph shows how many pounds each class has collected so far.
a) Record the amount collected by each class.
b) Before the next weigh-in, the amounts change:
1. Class C transfers \(10\,\text{lb}\) of paper to Class A.
2. Classes B and D combine their paper and divide it equally between the two classes.
How many pounds of paper does each class have after both changes?
c) Which class has the greatest amount at the end?

Hints
- Read each starting amount from the vertical scale.
- Complete the changes in the order given and record each new amount.
- When two amounts are combined and shared equally, add first and then divide by \(2\).
- Check that the total amount of paper remains the same.
Solution
1. Read the starting amounts: Class A, \(35\,\text{lb}\); Class B, \(50\,\text{lb}\); Class C, \(45\,\text{lb}\); Class D, \(20\,\text{lb}\).
2. After Class C transfers \(10\,\text{lb}\), Class A has \(35 + 10 = 45\,\text{lb}\), and Class C has \(45 - 10 = 35\,\text{lb}\).
3. Classes B and D have \(50 + 20 = 70\,\text{lb}\) together. Dividing equally gives \(70 \div 2 = 35\,\text{lb}\) for each class.
4. The final amounts are Class A, \(45\,\text{lb}\), and Classes B, C, and D, \(35\,\text{lb}\) each. Class A has the greatest amount.
Answer
a) Class A: \(35\,\text{lb}\); Class B: \(50\,\text{lb}\); Class C: \(45\,\text{lb}\); Class D: \(20\,\text{lb}\)
b) Class A: \(45\,\text{lb}\); Class B: \(35\,\text{lb}\); Class C: \(35\,\text{lb}\); Class D: \(35\,\text{lb}\)
c) Class A