What is the difference between change in quantity and change in quantity demanded? ​

A change in demand means that the entire demand curve shifts either left or right. A change in quantity demanded refers to a movement along the demand curve, which is caused only by a chance in price. ... In this case, the demand curve doesn't move; rather, we move along the existing demand curve.

isaiah walks 3 miles due north, turns and then 5 miles due east. how far is he from his starting point?

a^2 + b^2 = c^2

let c = distance from starting point.

(3)^2 + (5)^2 = c^2

9 + 25 = c^2

34 = c^2

sqrt{34} = sqrt{c^2}

sqrt{34} = c