Answer:
The expression that can be used to calculate the rate per second at which the machine launches the balls is fraction 20 over 4.
Explanation:
The x-axis label is Time in seconds, and the x-axis values are from 0 to 20 in increments of 4 for each grid line.
And the y-axis label is Number of Balls and the y-axis values from 0 to 100 in increments of 20 for each grid line.
If the ordered pairs (4,20) and (8,40) are on the graph, then the slope of the line will be represented by
Therefore, the expression that can be used to calculate the rate per second at which the machine launches the balls is fraction 20 over 4. (Answer)