9 because 18÷2=9
you can use models to help too
get 18 things and put them in 2 groups
Let the required no. be x then according to question
(84/100)*x = 21
x = 21*(100/84)
x = 2100/84
x = 25
hence the required no. is 25
hope it helped
Answer:
Because it is acorrding to question answer