Question

If x+y=(3.1.2) and x-y=(1.1.4) then find x.y​

Answer 1

$x + y = 312 ......(i)\\ x - y = 114.......(ii) \\ adding \: i \: and \: ii \: \\ \frac{x + y = 312}{x - y = 114} \\ solving \: we \: get \: \\ 2x = 426 \\ x = \frac{426}{2} \\ x = 213 \\ put \: x \: in \: eq \: i \: \\ x + y = 312 \\ 213 + y = 312 \\ y = 312 - 213 \\ y = 99$