The equation we'll be using to solve this is:
5.50x + 35 = y, where x is the number of weeks, and y is how much money he has
We're trying to find out how many weeks it takes Blake to raise $145, so we can plug that in for y and then solve for x
5.50x + 35 = 145
Subtract 35 from each side
5.50x=110
Divide each side by 5.5
x=20
The answer is A. at least 20 weeks