A class contains twice as many girls as boys. If the total number of the class is 48, how many boys are there in the class?
The total number of students in the class is 48. And so we can say that the number of girls plus the number of boys must be equal to 48. There are twice as many girls as boys. This means that if we take the number of boys and multiply it by two, it will be equal to the number of girls. Two times the number of boys equals the number of girls. And then the number of girls plus the number of boys must be equal to 48.
We can take this two 𝑏 and plug it in for 𝑔 in the first equation. And then we’ll have two 𝑏 plus 𝑏 equals 48. The coefficient of 𝑏 is one. Two 𝑏 plus one 𝑏 equals three 𝑏. If three times 𝑏 equals 48, we can divide both sides by three. And we’ll get that 𝑏 equals 16. 48 divided by three is 16.
This question is only asking for the number of boys in the class. And that would be 16. We can plug 16 back in to our original equation and use that to solve for the number of girls in the class by subtracting 16 from both sides, which gives us 32. There were 32 girls in the class. And this confirms that two times the number of boys, 16, equals the number of girls, 32. And our final answer is 16. That’s the number of boys there were in the class.