Answer:
the awnser is 9
Explanation:
because if it takes 7 h to make 21 k of dough that means every hour he makes 3 k of dough and to get to 27 we need to do this : 3x2=6 , and 21 +6= 27 and since every hour he makes 3 k of dough and we multiplyed 3x2 that means we have to add 7 +2=9 that is how we solve:)