A confectionery shop baked some egg tarts and packed them into 25 small boxes and 9 big boxes. There were an equal number of egg tarts in each small box and an equal number of egg tarts in each big box. Each big box contained 12 more egg tarts than each small box. 5/8 of the egg tarts baked were packed in small boxes. How many egg tarts were there in each small box?
so, if there were s tarts in a small box and b tarts in a big box, we have a total of 25s+9b eggs. Now we are told that
b = s+12
25s = 5/8 (25s+9b)
solve that to find s
Post your work if you get stuck