J's answer to Kishore's Secondary 1 Maths Singapore question.
done
{{ upvoteCount }} Upvotes
clear
{{ downvoteCount * -1 }} Downvotes
One unknown/variable way :
Let 2x be the price of A and 3x be the price of B.
Since ratio of A to B price is 2 : 3,
A/B = 2/3 (which equals 2x/3x)
Ratio of new price of A to new price of B = 10 : 11.
So New A / New B = 10/11
New A = 2x + 12, New B = 3x - 6
So (2x +12) / (3x - 6) = 10/11
Cross multiply,(or you can think of it as multiplying both side by the LCM of the denominators)
10(3x - 6) = 11(2x + 12)
30x - 60 = 22x + 132
Bring over the relevant terms to the other side,
30x - 22x = 132 + 60
8x = 192
x = 192/8 = 24
So 2x = 2(24) = 48, 3x = 3(24) = 72
Original price of A = $48, Original price of B = $72
Let 2x be the price of A and 3x be the price of B.
Since ratio of A to B price is 2 : 3,
A/B = 2/3 (which equals 2x/3x)
Ratio of new price of A to new price of B = 10 : 11.
So New A / New B = 10/11
New A = 2x + 12, New B = 3x - 6
So (2x +12) / (3x - 6) = 10/11
Cross multiply,(or you can think of it as multiplying both side by the LCM of the denominators)
10(3x - 6) = 11(2x + 12)
30x - 60 = 22x + 132
Bring over the relevant terms to the other side,
30x - 22x = 132 + 60
8x = 192
x = 192/8 = 24
So 2x = 2(24) = 48, 3x = 3(24) = 72
Original price of A = $48, Original price of B = $72
Date Posted:
3 years ago
360 Tutoring Program