Answer:
Step-by-step explanation:
y = ax + b
The trick is to solve for a.
y = 505
x = 8
b = 25
505 = a*8 + 25 Subtract 25 from both sides
-25 -25
480 = 8a
a = 60
What this means is that for each one of the 8 months, he added 60 dollars into his account
The equation is y = 60*x + 25