Step 1: Convert the given statement into a mathematical equation
The weight gain should be added to his original weight and the weight loss should be subtracted from it.
So,
Final weight =6512+125+114−516
=65×2+12+1×5+25+1×4+14−516
=130+12+5+25+4+14−516
=1312+75+54−516
Step 2: Convert the fractions into like fraction and find the final weight of Vijay
1312+75+54−516
=131×40+7×16+5×20−5×580
=5240+112+100−2580
= 542780kg
Hence, Vijay's weight after the third week is 542780 or 676780 kg