(30m+18n+42)(15m+25n+20)=450m^2+750mn+600m+270mn+450n^2+360n+630m+1050n+840=450m^2+1020mn+450n^2+1230m+1410n+840
(30m+18n+42)(15m+25n+20)=450m^2+750mn+600m+270mn+450n^2+360n+630m+1050n+840=450m^2+1020mn+450n^2+1230m+1410n+840