0.69x39+0.61x69
=0.69×（39+61）【运用乘法分配律】
=0.69×100
=69
望采纳
=0.69×39+61×0.39
=0.69×（39+61）
=0.69×100
=69
0.69x39+0.61x69
=0.69×39+61×0.69
=0.69×（39+61）
=0.69×100
=69
0.69×39 + 0.61×69
= 69×0.39 + 0.61×69
= 69×(0.39 + 0.61)
= 69×1
= 69
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