Given the following forecasting data, using trend projection, the slope of the prediction line is $$

Month Period Demand $($in

Thousands$)$

April

$1$

$19$

May

$2$

$20$

June

$3$

$18$

July

$4$

$19$

August

$5$

$17$

$-\mathrm{.}5$

$20\mathrm{.}1$

$10$

$-5$