The ratio of boys to girls in a class room was 9:8. Half of the girls left the classroom, and then there were 15 more boys than girls.

A. How many children were in the classroom in the beginning
B. How many girls left the classroom?

b/g = 9/8

b = g/2 + 15

So, to start with there were

27 boys and 24 girls

A. Well, to solve this riddle, we need to put on our math hats. So, the ratio of boys to girls in the beginning was 9:8. Let's assign variables to the number of boys and girls in the class, shall we? Let's say there were 9x boys and 8x girls initially. Following along? Great!

Now, after half of the girls, which is 4x, left the classroom, we are left with 9x boys and (8x - 4x) = 4x girls.

And we know that there were 15 more boys than girls. So, 9x - 15 = 4x.

Are you still with me? Good! Now we can solve the equation.

9x - 15 = 4x
Subtracting 4x from both sides, we get:
5x - 15 = 0

By adding 15 to both sides:
5x = 15

So, x = 3.

And since x represents the number of children, we multiply it by 17 (9 boys + 8 girls) to find the total number of children:
17 * 3 = 51.

Ta-da! There were 51 children in the classroom in the beginning.

B. Now, let's find out how many girls left the classroom. We know that half of the girls left, and since we started with 8x girls, that means 4x girls left.

Using our previous calculation, we found that x = 3. So, 4 * 3 = 12.

So, 12 girls left the classroom. They must have gone to some top-secret girl gang meeting or something. Who knows? But I hope they took notes for the ones who stayed!

To solve this problem, we can set up a system of equations:

Let's assume that there were 9x boys and 8x girls in the classroom initially.

After half of the girls left, the number of girls decreased to 8x/2 = 4x.

We are also given that there were 15 more boys than girls after the girls left. So, the number of boys would be 4x + 15.

Now, we can set up an equation using the given information:

9x / (4x + 15) = 9/8

To solve for x, we can cross multiply:

8 * 9x = 9 * (4x + 15)

72x = 36x + 135

36x = 135

Solving for x, we find that x = 3.75.

Since we are dealing with the number of children, we round up the value of x to the nearest whole number, which is 4.

A. So, in the beginning, there were 9 boys and 8 girls in the classroom. The total number of children is 9 + 8 = 17.

B. To find the number of girls who left the classroom, we substitute the value of x into our equation: 8x/2 = 8 * 4 / 2 = 16.

Therefore, 16 girls left the classroom.

In class there are 72 student. If the number of boys is half of number of girls,how many girls and boys are there in the class?

There would be 100