Answer:
y = 2.5(5^x)
Step-by-step explanation:
y = ab^x
(0, 2.5)
2.5 = ab^0
2.5 = a * 1
a = 2.5
y = 2.5b^x
312.5 = 2.5b^3
b^3 = 125
b = 5
