120 + 20x = y
explanation:
while the bank started off with 120 customers so that’s how we’re going to start it off
120 +
then later there is going to be around 20 new members each month which the x will help with that because that will be the x amount of people which you can double, triple, quadruple, that amount etc
120 + 20x
and the y will equal the whatever amount you got
120 + 20x = y