Question

there are 5 rupee notes and some 10 rupee notes. total amount of these notes together is 350 rupees. number of 5 rupee notes are less by 10 than twice number of 10 rupee notes. then find the number of 5 rupee and 10 rupee notes

Answer 1

Let the 5 rupee notes be x
Let the 10 rupee notes be y

5x +10y=350 (1st equation)

x=2y-10(given)

5(2y-10)+10y=350
10y-50+10y=350
20y=350+50
20y=400
y=20

x=2y-10
x=2(20)-10
x=30

there are 30 5 rupee notes and 20 10 rupee notes