Answer:
$50,000 was borrowed at 9%.
$125,000 was borrowed at 10%.
$75,000 was borrowed at 12%.
Explanation:
Let amount borrowed at 9% be x
Let amount borrowed at 10% be y
Let amount borrowed at 12% be z
Now equations form:
 ....(1)
 ....(1)
 ....(2)
 ....(2)
 ..... (3)
 ..... (3)
Substituting the value of y from (3) in (1) and (2)

=> 
 ......(4)
 ......(4)
 
 
=> 
 ....(5)
 ....(5)
Multiplying (4) by 0.12 and subtracting (5) from it, we get
 -
 - 


0.08x=4000
x = $50000
As y = 2.5x
So, 

y = $125000
And as x+y+z=250000
=>

z = $75000
Therefore, $50,000 was borrowed at 9%.
$125,000 was borrowed at 10%.
$75,000 was borrowed at 12%.