i need some help with this problem quick

Question

Ben fills 42 pints of juice in 12 in bottles, Six bottles have a capacity of 3 pints each. The remaining 6 bottles are all of the same capacity. Let b represent the capacity, in pints, of each of the remaining 6 bottles. What is the capacity of each of the 6 remaining bottles?

Answer 1

42 = 6 * 3 + 6 * b

42 = 18 + 6b

24 = 6b

b = 4