SOLUTION: There were p pupils in the junior class and they decided to spend D dollars on a school project to which all would contribute equally. Then 20 students refused to donate. How much

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Question 552313: There were p pupils in the junior class and they decided to spend D dollars on a school project to which all would contribute equally. Then 20 students refused to donate. How much more did each of the rest of the students have to donate?

Found 2 solutions by TutorDelphia, MathTherapy:
Answer by TutorDelphia(193) About Me  (Show Source):
You can put this solution on YOUR website!
Let's try this questions with some numbers in there first. Bare with me, it'll be much easier to do with the variables after we try this.
There were 100 pupils in the junior class and they decided to spend 10 dollars on a school project to which all would contribute equally. Then 20 students refused to donate. How much more did each of the rest of the students have to donate?
So the students are contributing a total of $1000 (100*10) and now just 80 are contributing. So that's $12.50 ($1000/80) for each student. So they each have to pay $2.50
So what were the calculations we did? We multiplied the number of students by their contribution, divided by the number of students minus 20 and then subtracted the original contribution
(100*10)/80-10
In place of the numbers, let's put the variables. But how did we get 80? We did 100-20
%28p%2Ad%29%2F%28p-20%29-d

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
There were p pupils in the junior class and they decided to spend D dollars on a school project to which all would contribute equally. Then 20 students refused to donate. How much more did each of the rest of the students have to donate?

Since total contributions are D dollars, then at first each was supposed to contribute D%2Fp

When 20 refused to donate, total contribution of D dollars remains the same, but the amount of students decreased by 20. Therefore, we have each now contributing:

D%2F%28p+-+20%29

This means that each would have to contribute: D%2F%28p+-+20%29+-+D%2Fp, or %28Dp+-+D%28p+-+20%29%29%2F%28p%28p+-+20%29%29, or highlight_green%2820D%2F%28p%5E2+-+20p%29%29 more

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