Answer:
210 people are there at the fair
Explanation:
Let the total number of people at the fair = X
People under 16 years old = 70% of X = 0.7 X
People remaining = Total number of people - Under 16 years
= X - 0.7X = 0.3X
The number of teachers = 1/3 of People remaining = 1/3 of 0.3X
Since there are 21 teachers
1/3 of 0.3X = 21
1/3 x 0.3X = 21
0.1X = 21
Divide both sides by the coefficient of X
0.1X/0.1 = 21/0.1
X = 210
That is 210 people are there at the fair