There are 40 children in a class. n of them do not wear spectacles. 4/5 of the boys and 2/3 of the girls wear spectacles. Express the number of boys who wear spectacles in terms of n.
b+g = 40
4/5 b + 2/3 g = 40-n
2/3 b + 2/3 g = 2/3 * 40
4/5 b + 2/3 g = 40-n
(4/5 - 2/3)b = 40-n - 2/3*40
2/15 b = 40/3 - n
b = 5(40-3n)/2 = 100 - 15n/2
Check: suppose n = 10
b = 25
g = 15
boys who wear: 20
girls who wear: 10
Thank you, Steve.
I dun understand
To express the number of boys who wear spectacles in terms of n, we'll need to calculate it based on the given information. Let's break down the problem and solve it step by step:
1. Let's represent the number of boys in the class as b and the number of girls as g.
From the information provided, we know that there are 40 children in total in the class.
So we can write the equation: b + g = 40.
2. We're also given that n children do not wear spectacles, but it doesn't specify if they are boys, girls, or a combination of both.
So, let's assume that n represents the number of boys and girls who do not wear spectacles.
Therefore, the number of children who wear spectacles will be (40 - n).
3. We're told that 4/5 of the boys wear spectacles. This means that out of all the boys (b), 4/5 of them wear spectacles.
So, the number of boys who wear spectacles is (4/5) * b.
4. We're also told that 2/3 of the girls wear spectacles. Similar to above, the number of girls who wear spectacles is (2/3) * g.
5. Now, let's substitute the values from step 3 and 4 into the equation from step 2:
(4/5) * b + (2/3) * g = (40 - n).
By following this process, you can express the number of boys who wear spectacles in terms of n.