the product of mona's age five years ago and her age 8 years later is 30 find her present age.
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hey mate.
assume present age of mona be n.
=) (n-5) (n+8) = 30
=) n(n+8) - 5(n+8) = 30
=) n² + 8n - 5n - 40 = 30
=) n² + 3n - 40 = 30
=) n² + 3n - 40 - 30 = 0
=) n² + 3n - 70 = 0
=) n² + 10n - 7n - 70 = 0
=) n(n+10) - 7(n+10) = 0
=) (n-7) (n+10) = 0
hence n = 7.
assume present age of mona be n.
=) (n-5) (n+8) = 30
=) n(n+8) - 5(n+8) = 30
=) n² + 8n - 5n - 40 = 30
=) n² + 3n - 40 = 30
=) n² + 3n - 40 - 30 = 0
=) n² + 3n - 70 = 0
=) n² + 10n - 7n - 70 = 0
=) n(n+10) - 7(n+10) = 0
=) (n-7) (n+10) = 0
hence n = 7.
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