Question

3. The sum of the Ages of the brother & Sister
at
present 21. five years ago the product of their Ages was 28 years. what is the age of the brother and sister age?
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Answer 1

Answer: Answer:   A) 9, 12

Step-by-step explanation:   pls trust

Answer 2

Let

x=brother's age

y=sister's age

Sum of their ages

x+y=21 ------Eq(1)

5 years ago the pruduct of their ages:

(x-5)(y-5)=28 -----Eq(2)

From Eq(1):

y=21-x

Pur in Eq(2):

(x-5)(21-x-5)=28

(x-5)(16-x)=28

16x-x²-80+5x=28

21x-x²-80-28=0

21x-x²-108=0

-x²+21x-108=0

x²-21x+108=0

x²-12x-9x+108=0

x(x-12)-9(x-12)=0

(x-9)(x-12)=0

x-9=0 ; x-12=0

x=9 ; x=12

Put x=9 in Eq(1)

9+y=21

y=21-9

y=12

Now put x=12 in Eq(1)

12+y=21

y=21-12

y=9

So If brother is 12 years old than sister is 9 years old and if brother is 9 years old than sister is 12 years old respectively.