3 litres of fruit juice plus 4 litres of lemonade will make 3 + 4 = 7 litres of fruit punch. To make 42 litres of fruit punch Josie would need to multiple these quantities by 4 (as 4 x 7 = 42). she would need 4 x 3 = 12 litres of fruit juice and 4 x 4 = 16 litres of lemonade.
