Question

The ages of A and B are in the ratio 5 : 3. After 6 years, their ages will be in the ratio 7 : 5.
The present age of A is ...
1 point
5 years
10 years
15 years
20 years​

Answer 1

ɢɪᴠᴇɴ :-

☀ ʀᴀᴛɪᴏ ᴏғ ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇꜱ ᴏғ ᴀ ᴀɴᴅ ʙ = 5 : 3

☀ ʀᴀᴛɪᴏ ᴀғᴛᴇʀ 6 ʏᴇᴀʀꜱ = 7 : 5

ᴛᴏ ғɪɴᴅ :-

☀ ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇ ᴏғ ᴀ

ꜱᴏʟᴜᴛɪᴏɴ :-

☀ ʟᴇᴛ ᴛʜᴇɪʀ ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇꜱ ʙᴇ ᴀᴄᴄᴏʀᴅɪɴɢ ᴛᴏ ᴛʜᴇ ʀᴀᴛɪᴏ :

  ᴀ = 5x

  ʙ = 3x

☀ ᴀғᴛᴇʀ 6 ʏᴇᴀʀꜱ

  ᴀ = 5x + 6

  ʙ = 3x + 6

☀ ᴀᴛϙ :

$\sf \implies \dfrac{5x+6}{3x+6} = \dfrac{7}{5}$

$\sf \{Cross\;Multiply\}$

$\sf \implies 25x+30 = 21x + 42$

$\sf \implies 4x = 12$

$\sf \implies x = \dfrac{12}{4} = 3$

☀ ʟᴇᴛ'ꜱ ғɪɴᴅ ᴛʜᴇɪʀ ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇꜱ ʙʏ ꜱᴜʙꜱᴛɪᴛᴜᴛɪɴɢ ᴛʜᴇ ᴠᴀʟᴜᴇꜱ !

ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇ ᴏғ ᴀ  = 5x  = 5 × 3 = 15 ʏᴇᴀʀꜱ

ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇ ᴏғ ʙ = 3x = 3 × 3 = 9 ʏᴇᴀʀꜱ

∴ ᴘʀᴇꜱᴇɴᴛ ᴀɢᴇ ᴏғ ᴀ ɪꜱ 15 ʏᴇᴀʀꜱ

_______

ᴀʟʟ ᴅᴏɴᴇ ! :ᴅ

Answer 2

Answer:

15 years, i hope this trick would help u