Bella and Justin went to the bank to open new checking accounts. The equation C = 0. In +1.50 represents the monthly cost, C, in dollars, where n is the number of checks written by Bella. In Justin's account, the monthly cost is proportional to the number of checks written. The monthly cost for Justin's account is $1.20 for writing 3 checks. How many checks must Bella and Justin write, if any, so that the cost of the accounts is the same for one month? What is the cost, if any?​