Question

this graph shows how the number of spools of thread that tessa has left is related to the number of comforters that she makes.
if tessa makes 5 comforters, how many spools of thread will she have left?
\boxed{} spools of thread

Explanation:

Step1: Determine the slope of the line

The graph starts at (0, 100) and let's find another point. Let's take (10, 60) (assuming from the grid). The slope $m=\frac{y_2 - y_1}{x_2 - x_1}=\frac{60 - 100}{10 - 0}=\frac{-40}{10}=-4$. So the equation is $y = - 4x+100$, where $x$ is the number of comforters and $y$ is spools remaining.

Step2: Substitute x = 5 into the equation

Substitute $x = 5$ into $y=-4x + 100$. So $y=-4\times5 + 100=-20 + 100 = 80$? Wait, no, maybe my initial point is wrong. Wait, looking at the graph, when x=0, y=100. When x=10, y=60? Wait, no, maybe the grid is different. Wait, let's check the graph again. The y - axis: 100, 90, 80, 70, 60, 50,... The x - axis: 0,1,2,3,4,5,6,7,8,9,10. Let's find two points. At x = 0, y=100. At x = 10, y=60? No, wait, when x=0, y=100. Let's see the line: from (0,100) to (10,60)? Wait, no, maybe the slope is - 4? Wait, no, 100 - 60 = 40 over 10 units, so 4 per unit. Wait, but when x=5, let's see the graph. The line goes from (0,100) down to (10,60). So the equation is $y=100 - 4x$. So when x = 5, $y=100-4\times5=100 - 20 = 80$? Wait, but maybe the graph has a different slope. Wait, maybe the correct points are (0,100) and (5, 80)? Wait, no, let's look at the graph again. Wait, the y - axis: 100 at x=0, then at x=5, what's the y? Let's see the grid. Each x - unit, the y decreases by 4? Wait, 100 - 45=80. Wait, but maybe I made a mistake. Wait, let's check the graph: when x=0, y=100. When x=1, y=96? No, maybe the slope is - 4. So for x=5, y=100 - 45=80. Wait, but maybe the graph is such that from (0,100) to (10,60), so the slope is (60 - 100)/(10 - 0)=-4. So equation y = - 4x+100. So x=5: y=-20 + 100=80. Wait, but maybe the graph is different. Wait, another way: count the grid. From x=0 (100) to x=5: how much does it decrease? Each x - step (1 comforter) decreases by 4? So 5*4 = 20, 100 - 20=80. So when x=5, y=80.

Wait, maybe my initial point was wrong. Wait, let's look at the graph again. The y - axis: 100, 90, 80, 70, 60, 50,... The x - axis: 0,1,2,3,4,5,6,7,8,9,10. The line goes from (0,100) to (10,60). So the equation is $y = 100-4x$. So when x = 5, $y=100 - 4\times5=80$.

Answer:

80