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【题目】一个长方形的周长是72厘米,如果这个长方形的长减少1/5,宽增加1/4,而长方形的周长不变。那么,这个长方形的长和宽各是多少厘米?【一般解法】已知长方形的周长,求长和宽,是一道逆思考的问题,通常用列方程的方法来解答。设这个长方形的宽是a厘米,长是b厘米。则:a+b=72÷2=36。根据长方形的宽增加1/4,长减少1/5,周长仍和原来一样,可以列出方程:
【Subject】 The circumference of a rectangle is 72 cm. If the length of the rectangle is reduced by 1/5, the width is increased by 1/4, while the circumference of the rectangle is unchanged. So, the length and width of the rectangle is the number of centimeters each? [General solution] known perimeter, length and width, is a question of inverse thinking, usually using the column equation method to answer. Let this rectangular width is a centimeter, length is b centimeters. Then: a + b = 72 ÷ 2 = 36. According to the width of the rectangle to increase 1/4, the length reduced by 1/5, the perimeter is still the same, you can list the equation: