B because the amount of money they earn per hour multiplied by how many hours they worked is equal to what they earned in total
GIVEN
1) Females outnumber males by 3 to 2.
2) There are 1770 people in the city.
SOLUTION
Let the number of males be x and the number of females y. Therefore, the total number of people can be written to be:

If there are 3 females for every 2 males, we have that:

We can substitute equation (2) into equation (1) and solve for y:

Dividing both sides by 5, we have

There are 1062 females in the county.
Givens
x + y = 3
x =6 - 4y
Solution
Use the top equation to substitute for x in the second equation.
x = 3 - y
Put this result into the second given equation and solve for y
3 - y = 6 - 4y Add 4y to both sides.
3 - y + 4y = 6 Combine on the left
3 + 3y = 6 Subtract 3 from both sides
3 - 3 + 3y = 6 - 3 Combine
3y = 3 Divide by 3
3y/3 = 3/3 Combine
y = 1
=========================
x + y = 3 but y = 1
x + 1 = 3 Subtract 1 from both sides.
x + 1 - 1 =3 - 1
x = 2
Answer
x = 2
y = 1
So what you have to do to figure this out is 47-20 to get 27, then take 27 and divide it by 3 to get the answer of 9 comic books were sold by John.