Aretiree invests $1240 for 3.5 years in a savings plan that pays a simple interest of 2.1% per year. how much interest will be earned?

Step-by-step explanation:

I=Prt

I=1240*.021*3.5=91.14

first blank: b/a

second blank: (b, 0)

third blank: -a/b

fourth blank : -1  

Step-by-step explanation:

To calculate the slope you need two points as coordinates (x,y). Points on line s: (-a, 0) and (0, b).  The formula is:

slope: (y2 - y1)/(x2 - x1) = (b - 0)/(0 - (-a)) = b/a

Rotation 90° clockwise translate point (x, y) -> (y, -x). Then, (-a, 0) -> (0, a) and (0, b) -> (b, 0)

The points on line t are: (b, 0) and (0, a).  Then, the slope is

slope: (y2 - y1)/(x2 - x1) = (a - 0)/(0 - b) = -a/b

The product of the slopes is: (b/a)*(-a/b) = -1, therefore, the lines are opposite reciprocals.