Question

plese tell me these questions

Answer 1

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QUESTION :

✓ Five years ago a man was seven times as old as his son . Five years hence, the father will be three times as old as his son. find their present ages ✓

SOLUTION :

The equation will obtain =>
(i).

=> x - 5 =7( y - 5)

=> x - 5 = 7y -35

=> x - 7y = - 35 + 5

=> x - 7y = -30 (i) equation..................

(ii). x + 5 = 3( y + 5 )

=> x + 5 = 3y + 15

=> x - 3y = 15 - 5

=> x - 3y = 10 (ii). equation............. . ..

=> by eliminating them (i) and (ii).

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \bf{ \cancel{x} - 7y = - 30} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \bf{ \cancel{x} - \: 3y = 10 } \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: - \: \: \: \: \: \: + \: \: \: \: \: \: - \\ \: \: \: \: \: \: \: \: \: \: \: - - - - - - - - \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \bf{ \cancel{-} 4y = \: \: \: \: \cancel{ - }40 } \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \bf{ y = \frac{ \cancel{40 }^{ \: \: 10} } { \cancel{4 }} } \\ \: \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: y = 10$
putting this value of y in the first equation =>

=> x - 7y = -30

=> x - 7(10) = -30

=> x = -30 + 70

=> x = 40

we have consider X = father age and Y = son's age.

present age of father be , x = 40

present age of son be y

y = 10