How to graph y=5-1/2x

 Plot the y-intercept in the y-axis, then use the slope to determine one or two more coordinates to draw the line through.

Step-by-step explanation:

Step 1.) Rewrite it in slope-intercept form so it is clear what the values for slope and y-intercept are.

y = mx + b  

b is the y-intercept. it is the "constant" not a variable

m is the slope. The numerator is the change in y-values, up or down, the denominator is the change in x-values going left to right.

This equation becomes y = -1/2 x +5

Step 2.)  On the coordinate plane (graph paper with an x-axis and y-axis), put a point at +5 on the y-axis.

Step 3.) Use the values in the slope -1/2 to locate another point. Negative 1 means down one square from the y-intercept. 2 means move to the right 2 squares. So your coordinate is (2,4) for this point. Plot one more, down one and two to the right from there. It will be at (4,3)

Step 4.) Use a straight edge lined up (carefully) on the three points and draw the line across the entire coordinate plane. (Some teachers require arrows on each end of the line too.)

That's it. It may be good to write the equation near the graph.

The attachment shows the graph of this equation with points labeled.

6 adults and 9 children went.

a + c = 15

12a + 9c = 153

12(6) + 9(9) = 153

72 + 81 = 153