Put the following equation of a line into slope-intercept form, simplifying all fractions.

3x+9y=63

To put the equation 3x + 9y = 63 into slope-intercept form, which is in the form y = mx + b, where m represents the slope and b represents the y-intercept, we need to isolate y on one side of the equation.

Start by subtracting 3x from both sides to get:
9y = -3x + 63.

Next, divide both sides by 9 to simplify the fraction:
y = (-3/9)x + 63/9.

Further simplifying the fraction gives:
y = (-1/3)x + 7.

Thus, the equation 3x + 9y = 63 in slope-intercept form is y = (-1/3)x + 7.