In an envelope there are some ₹5 notes and some ₹10 notes. Total amount of these notes together is ₹350. Number of ₹5 notes are less by 10

Let the number of ₹5 notes be ‘x’ and the number of ₹10 notes be ‘y’

 Total amount of x notes of ₹ 5 = ₹ 5x 

Total amount ofy notes of ₹ 10 = ₹ 10y 

∴ Total amount = 5x + 10y

 According to the first condition, 

total amount of the notes together is ₹350. 

∴ 5x + 10y = 350 …(i) 

According to the second condition,

Number of ₹ 5 notes are less by 10 than twice the number of ₹ 10 notes.

∴ x = 2y – 10 

∴ x – 2y = -10 …..(ii) 

Multiplying equation (ii) by 5,

5x – 10y = -50 …(iii)

Adding equations (i) and (iii),

 5x + 10y =350 

+ 5x – 10y = -50 

10x =300 

∴ x = \(\frac{300}{10}\)

∴ x = 30 

Substituting x = 30 in equation (ii)

, x – 2y = -10 

30 – 2y = -10 

∴ 30 + 10 = 2y 

∴ 40 = 2y

∴ y = \(\frac{40}{2}\)

∴ y = 20 T

here are 30 notes of ₹ 5 and 20 notes of ₹ 10 in the envelope.