80%; 76%; 48%; 32%,от 60. 3,6% от 28, 145, 280, 1250

а)(6+4)*8=6*8+4*8=48+32=80; (6+7)*8=6*8+7*8=48+56=104; (10+7)*3=10*3+7*3=30+21=51

б)(7+8)*6=7*6+8*6=42+48=90; (13+7)*4=13*4+7*4=52+28=80; (20+8)*5=20*8+8*5=160+40=200

в)(12+18)*6=12*6+18*6=72+108=180; (15+7)*100=15*100+7*100=1500+700=2200; (100+70)*4=100*4+70*4=400+280=680