Answer:
y = 5 * (1/2)^x
Explanation:
This is an exponential function
y =ab^x
where a is the initial value ( where x = 0)
a = 5
y = 5 * b^x
Pick a point to determine b
(1,2.5)
2.5 = 5 * b^1
2.5 = 5 *b
Divide each side by 5
2.5/5 = b
b = 1/2
y = 5 * (1/2)^x