Treat the data as ordered pairs. From the table, write the year as x - coordinate and the percent as y - coordinate.

Plot the ordered pairs as points in a coordinate plane.

The scatter plot shows a negative correlation between x and y. This means that as the x - values increased, the y - value tended to decrease, so you can fit a line to the data.

Draw a line that appears to fit the points in the scatter plot closely.

Write an equation using any two points on the line.

Substitute the values of in the slope formula .

.

To write the line equation, we can use either of the two given points.

Consider the point .

Substitute in point-slope form equation or .

Apply distributive property: .

Add 65.7 to each side.

.

The line equation is .

Substitute the value of in the above equation.

.

The missing value is , the equation is and its graph is