1. **State the problem:** We have a line given by the equation $y = ax + b$ where $a = 0.6$ and we need to find the value of $b$. 2. **Recall the formula:** The equation of a line is $y = ax + b$ where $a$ is the slope and $b$ is the y-intercept (the value of $y$ when $x=0$). 3. **Identify the y-intercept:** From the graph, the line crosses the y-axis at about $y = 100$. Since the y-intercept is the point where $x=0$, this means $b = 100$. 4. **Verification using a point:** The line passes through the point $(50, 400)$. Substitute $x=50$, $y=400$, and $a=0.6$ into the equation: $$400 = 0.6 \times 50 + b$$ $$400 = 30 + b$$ 5. **Solve for $b$:** $$b = 400 - 30 = 370$$ 6. **Check consistency:** The y-intercept from the graph was about 100, but calculation using the point gives $b=370$. This suggests the y-intercept is actually $370$, not $100$. The graph's estimate was approximate. **Final answer:** $$a = 0.6, \quad b = 370$$