The slope of a line indicates how much change occurred. Depending on what the line graphs in macroeconomics, the slope could show how quickly supply responds to demand or demand to price. More generally, the slope equals the rise over the run of the equation.
Things You'll Need
 Graphed line
 Calculator

Choose two points along the line on the macroeconomics graph. For instance, if you graphed price and demand, with the prices on the yaxis (vertical) and the quantity demanded on the xaxis (horizontal), you can choose the following points: (5, $4) and (6, $2).

Subtract the yvalues (prices) by taking the price amount of the second point with the smaller x value from the price amount from the first point with the larger quantity demanded to find the change in price. For example: $2  $4 =  $2. A negative number indicates that the slope decreases.

Subtract the smaller quantity demanded from the larger xvalue to find the change in quantity demanded. For the example: 6  5 = 1.

Divide the change in price (change in x) by the change in quantity demanded (change in y). For the example: 2/1 = 2. The slope of $2 indicates that for every $2 the price increases, the quantity demanded decreases by one.
References
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