Question

a number of girls in class is 99 more than the number of boys. if there are 39 students in all, how many girls are there in the class?

Answer 1

Let x be the number of boys in the class.
Then the number of girls is x + 99.
Since there are 39 students in all, we have:
x + (x + 99) = 39
2x + 99 = 39
2x = -60
x = -30

However, since the number of boys cannot be negative, the assumption that x is the number of boys is incorrect.
Let's try again with the correct assumption:
Let x be the number of girls in the class.
Then the number of boys is x - 99.
Since there are 39 students in all, we have:
x + (x - 99) = 39
2x - 99 = 39
2x = 138
x = 69

Therefore, there are 69 girls in the class.