The sum of two positive integers is 80 & difference between them is 20. Then what is difference of squares of those numbers ?
Let the positive integers be $$x$$ and $$y$$
Sum = $$x+y=80$$ -------(i)
Difference = $$x-y=20$$ -----(ii)
$$\therefore$$ Difference of squares = $$x^2-y^2=(x+y)(x-y)$$
= $$80 \times 20=1600$$
=> Ans - (B)
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