
Step 1: Relation between Y in 2019 and 2020.
Given: \[ Y_{2020} = 1.25 \times Y_{2019} \] From the graph, \(Y_{2020} = 75,000\). \[ Y_{2019} = \frac{75,000}{1.25} = 60,000 \]
Step 2: Relation between Z in 2019 and 2020.
Given: \[ Z_{2019} = 0.8 \times Z_{2020} \] From the graph, \(Z_{2020} = 50,000\). \[ Z_{2019} = 0.8 \times 50,000 = 40,000 \]
Step 3: Read values of X and Z in 2015 from the graph.
From the graph: \[ X_{2015} = 70,000, \quad Z_{2015} = 45,000 \]
Step 4: Total pens sold (X + Z in 2015).
\[ \text{Total} = X_{2015} + Z_{2015} = 70,000 + 45,000 = 1,15,000 \]
\[ \boxed{1,15,000} \]




