SAT数学题,求翻译和讲解
问题描述：
SAT数学题,求翻译和讲解
A rectangular floor 18 feet by 10 feet is to be completely covered with carpeting that costs x dollars per square yard. In terms of x, how many dollars will the carpeting cost? (1 yard=3 feet)
A20x B28x C60x D180x E540x
答案是A,求讲解
答
一个18英尺×10英尺的矩形场地铺满地毯,地毯的价格是每平方码x美元.请用包含x的式子表示地毯的总价格.（提示：1码 = 3英尺）
1码 = 3英尺,所以1平方码 = 9平方英尺
18×10 = 180平方英尺 = 20平方码
所以总价格为20x