Your question:
a purse contains $250 in notes of denominations of 10 and 50. if the number of $10 notes is one more than of $ 50 notes, find the number of notes of each denomination

Solution:
Let the number of $50 notes be x
Then number of $10 notes = x + 1

Value of the $50 notes = 50*x
Value of the $10 notes = 10*(x + 1)

Total value = 250

So 





There are 4 $50 notes and 5 $10 notes.

:)