The gradient formula is (y2-y1)/(x2-x1) aka rise/run, where by (x1,y1) and (x2,y2) are two points on the line.
In this case, the gradient
= -5-(-2))/(2-(-2))
= -3/4
If you would like to write each rate as a unit rate, you can do this using the following steps:
$2 ... 5 cans of a soup
$1 ... x cans of a soup = ?
2 * x = 5 * 1
2 * x = 5
x = 5 / 2
x = 2.5 cans of a soup per $1
$2 ... 5 cans of a soup
$x = ? ... 1 can of a soup
2 * 1 = 5 * x
2 = 5 * x
x = 2 / 5
x = $0.4 per 1 can of a soup
1.25/20=1x
1.25x=20
x=20/1.25=16
1 inch=16 feet
4/5 -3/7=
28/35 -15/35
=13/35
The equation of a circle:

(h,k) - the coordinates of the center
r - the radius
The center is (4,0), the length of the radius is 2√3.