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六年级数学老师给同学们布置了一道思考题:把一个长方形分成4个小三角形,绿色三角形的面积占长方形面积的15%,黄色三角形的面积是21平方厘米。这个长方形的面积是多少平方厘米?面对这道题,刘云认真思考起来。过了一会儿,她说:“通过题目已经告诉我们的条件,如果知道21平方厘米占整个图形的百分之几,那么就能很快求出长方形的面积。怎样才能知道这个百分之几呢?看来
Sixth grade mathematics teacher to the students arranged a question: a rectangle is divided into four small triangles, green triangles accounted for 15% of the rectangular area, the area of the yellow triangle is 21 square centimeters. The rectangular area is the number of square centimeter? Faced with this issue, Liu seriously consider it. After a while, she said: ”The conditions already told us through the subject, if we know that 21 square centimeters make up a few percent of the total figure, then we can find the area of the rectangle quickly. How can we know this percentage It seems