列式計(jì)算
①320比一個(gè)數(shù)少65,這個(gè)數(shù)是多少?(先列含未知數(shù)x的等式,再解答)
②42與18的積減去350與180的和,差是多少?
③148加上576除以32的商,所得的和再乘25,積是多少?
解:①設(shè)這個(gè)數(shù)是x,由題意得:
x-320=65,
x-320+320=65+320,
x=385;
答:這個(gè)數(shù)是385.
②42×18-(350+180),
=756-530,
=226;
答:差是226.
③(148+576÷32)×25,
=(148+18)×25,
=166×25,
=4150;
答:積是4150.
分析:①此題可設(shè)這個(gè)數(shù)為x,根據(jù)“320比一個(gè)數(shù)少65”列出方程x-320=65,解方程即可;
②求差,就要知道被減數(shù)和減數(shù)分別是多少,被減數(shù)是“42與18的積”,減數(shù)是“350與180的和”,列式為42×18-(350+180),解答即可;
③所得的和再乘25,求積是多少,根據(jù)題意,和是(148+576÷32),積為(148+576÷32)×25,解答即可.
點(diǎn)評(píng):此題考查了學(xué)生對(duì)文字?jǐn)⑹鲱}的理解情況,以及列式計(jì)算的能力.