21×(36+79)=21*36+21*79= 756+1659=2415
21×(36+79)=21*115=2415
15×(55+75-10)=15*55+15*75-15*10=825+1125-150=1800
15×(55+75-10)=15*120=1800
27×(567-456)=27*567-27*456=15309-12312= 2997
27×(567-456)= 27*111= 2997
135×(13+11+1-20)=135*13+135*11+135-135*20=1755+1485+135-2700=
= 675
135×(13+11+1-20)=135* 5=675
20×(139378-138288)=20×139378 -20×138288= 2787560 - 2765760=
= 21800
20×(139378-138288)=20*1090= 21800
(68+42)×96 = 68*96 +42*96=6528 + 4032=10560
(68+42)×96 = 110*96=10560
