Question

Practice set 3.2 (1) In an envelope there are some 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 number of 10 rupee notes. Then find the number of 5 rupee and 10 rupee notes. ​

Answer 1

Answer:

Let the number of ₹5 note be x .

• Let the number of ₹10 note be y .

$\underline{ \sf \: \green{Given:}}$

⟹ First condition .

in an envelope there are ₹5 notes and ₹10 notes

and there sum is ₹350

⇒ 5x + 10y = 350 ( divided by 5 )

⇒ x + 2y = 70 ——— (l)

⟹ second condition .

no.of ₹5 notes are less by ₹10 note by 10.

⇒ x - y = 10 ——— (ll)

• subtracting ——— (l) & (ll)

x + 2y = 70

– x – y = 10 ( x and x will cut )

3y = 60

$\sf \: y=\frac{60}{3}$

$\sf\mathcal\orange{★ \sf \: \:y\: =\: 20 \:★}$

Substituting value of y = 20 in ——— (ll)

⇒ x – y = 10

⇒ x – 20 = 10

⇒ x = 10 + 20

⇒ x = 30

$\sf{★\ \sf:x\: =\: 30 \:★★ \sf \: \:y\: =\: 20 \:★}$

number of 5 rupee notes are 30

number of 10 rupee notes are 20