To determine the slope-intercept form of the equation of the line representing the number of seventh graders (y) and eighth graders (x) who attended the dance, we can use the information provided: a total of 275 students attended the dance.
In mathematical terms, this can be represented as: \[ x + y = 275 \]
Now, we need to express this equation in slope-intercept form, which is: \[ y = mx + b \] where \( m \) is the slope and \( b \) is the y-intercept.
Starting with the original equation: \[ y = 275 - x \]
Now, we can rearrange it to fit the slope-intercept form: \[ y = -1x + 275 \]
Thus, the slope-intercept form of the equation is: \[ y = -x + 275 \]
From this, we can see that the slope \( m \) is -1 and the y-intercept \( b \) is 275.
To answer the question: The slope-intercept form of the equation for the line is: \[ y = -x + 275 \]