239×7.2+956×8.2 =239×7.2+956×7.2+956 =7.2×(239+956)+956 =7.2×1195+956 =7.2×1000+7.2×200-7.2×5+956 =7200+1440+956-36 =8640+920 =8640+1000-80 =9640-80 =9560
239x7.2+239x8.2x4=239x(7.2+32.8)=239x40=9560