a sum of 500 is in the form of denominations of 5 and 10. if the total number of notes is 90, find the number of notes of each type.

Let x be the number of notes of denomination Rs5 Let y be the number of notes of denomination Rs10 we know that the total amount is Rs500 which means 5 times the number of notes of denom Rs5 + 10 times the number of notes of denomination Rs 10 equals 500 ie. 5x+10y=500 Also total number of notes is 90 ie x+y=90 hence x=90-y 5*(90-y)+10y=500

**450-5y+10y=500 5y=500-450 5y=50 y=50/5 y=10 x=90-y=90-10=80 hence 10 notes of Rs10 and 80 notes of Rs5**