Answer :
If the sum of three numbers is 20 , then the product of all the three numbers is 28 .
In the question ,
the sum of three numbers is given as = 20 ,
let the three numbers be x₁ , x₂ and x₃ .
So , x₁ + x₂ + x₃ = 20 ,
the first number is 4 times the sum of other two ,
that is , x₁ = 4(x₂ + x₃) ;
and the second number is 7 times the third ,
that is , x₂ = 7x₃
Substituting the values from above in the sum equation ,
we get ,
4(x₂ + x₃) + 7x₃ + x₃ = 20
4(7x₃ + x₃) + 7x₃ + x₃ = 20
32x₃ + 8x₃ = 20
40x₃ = 20
x₃ = 1/2
So , x₂ = 7/2 and
x₁ = 4(7/2 + 1/2) = 32/2 = 16
So ,the product is = 16×(7/2)×(1/2)
= 28 .
Therefore , the product is 28 .
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