Question 12409
Let X people pledge $50.
Then 2X people pledged $25

Total money given= 50xX + 25x2X = 100X

We know that total money coming in = $18000
So 100X = 18000
X = 18000/100

So X = 180 i.e. 180 people pledged $50
So 2x180 = 360 people pledged $25