while True:
    cost = float(input("Enter cost price: "))
    if cost <= 0:
        break
    print("The retail price is %.2f" % (cost*1.25))

cac8ed44cee7eab52aa7c8deaf37b4f397aa282c
<mask token>

while True:
    cost = float(input('Enter cost price: '))
    if cost <= 0:
        break
    print('The retail price is %.2f' % (cost * 1.25))

while True:
    cost = float(input("Enter cost price: "))
    if cost <= 0:
        break
    print("The retail price is %.2f" % (cost*1.25))
