If we are given the equation y = -27x + 577 and that
x = weeks
y = money left in account
Then you must replace 145 (the money) for y and solve for x (the weeks)
145 = -27x + 577
145 - 577 = -27x + 577 - 577
-432 = -27x
-432/-27 = -27x/-27
16 = x
This means that after 16 weeks Alma will have $145 left in her account
Hope this helped!
~Just a girl in love with Shawn Mendes