1③
245(29xy-18x+118y)-218(154xy+32x+6y)
分配法則でかっこを開き、同類項をまとめる。
245(29xy-18x+118y)-218(154xy+32x+6y)
=1615xy-35x+415y-512xy-16x-23y
=(1615-512)xy+(-35-16)x+(415-23)y
=(64-2560)xy+(-18-530)x+(4-1015)y
=3960xy-2330x-615y
=1320xy-2330x-25y
