Lily has $45 in her school lunch account. if she spends $2.50 each day, which graph represents lily's account balance, y, after she buys lunch for x days?

Y = -2.5x + 45

That's your equation. Your y-intercept would be 45 because that's what she started with. It would be a negative slope as well.

Y = -2.50x
(it is negative cuz she is takig out 2.50 each day so her balance is decreasing)

45 = -2.50x

so she could by 18 lunches

so since there are no graphs, its the graph with (18,0) as a valid point and a slope of -2.5. hope this makes sense and helps