用简便方法计算38x7.5-35x3.8+0.3x - 知识问答

用简便方法计算38x7.5-35x3.8+0.3x15+20.5x7／一

2个回答

原式=19x2x7.5+0.3x15+20.5x7-35÷5x3.8x5
=19x15+0.3x15+20.5x7-7x19
=(19+0.3)x15+(20.5-19)x7
=19.3x15+1.5x7
=19.3x15+1.5x10x0.7
=19.3x15+15x0.7
=(19.3+0.7)x15
=20x15
=300

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