1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

# Rahman bought 30 stamps consisting of 20 paise and 30 paise stamps. Given that the stamps cost Rs.7.80 altogether, how many 20 paise stamps did he buy?

A
12
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
14
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
C
16
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
D
18
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
Open in App
Solution

## The correct option is A 12Rahman bought 30 stamps consisting of 20 paise and 30 paise stamps and total stamps cost Rs 7.80.Let 20 paise stamps are x and 30 paise stamps are yThen x+y=30 ............. (i)Cost of 20 paise stamps =0.20xCost of 30 paise stamps =0.30xBut total cost of stamps is Rs 7.80Then, 0.20x+0.30y=7.80 ............. (ii)Multiply (ii) by 10, we get0.20x×10+0.30y×10=7.80×102x+3y=78 ............... (iii)Also, from (i)3×x+3×y=3×30⇒3x+3y=90.............. (iv)Subtract (iv) with (iii), we get (3x+3y)−(2x+3y)=90−78⇒3x+3y−2x−3y=12⇒x=12Then 20 paise stamps are 12.

Suggest Corrections
0
Join BYJU'S Learning Program
Related Videos
Algebraic Solution
MATHEMATICS
Watch in App
Join BYJU'S Learning Program