(343 x 343 x 343 + 257 x 257 x 257 ) / (343 x 343 - 343 x 257 + 257 + 257) =?

Given Exp. = ( a³ + b³ ) / ( a² - ab + b² ), where a =3 42, b = 257
= [(a + b )(a² - ab +b²)] / (a² - ab + b²)
= a + b
= 343+257
= 600.