Question

the product of mona's age five years ago and her age 8 years later is 30 find her present age.

Answer 1

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.