16xy 4 +4x 2 y 3 -12x 5 y 4 =
If there is no symbol between a letter and a number, or between two letters then there IS an INVISABLE TIMES SIGN
16xy 4 +4x 2 y 3 -12x 5 y 4
= 16xy*4 +4x*2*y*3 -12x*5*y*4
= 64xy + 24xy - 240xy
=(64+24-240)xy
and you can finish it
