5道英语数学题,
1）if the price of an item(商品) decrease from(减少) $30 to $24,what is the percent(百分数) decrease in price?
2)what is the ratio(比) of the perimeter(周长) of a pentagon(五边形) with each side(边长) of length(长度) 6 to the perimeter of an octagon(八边形) with each side of length
3)if x,y and z are positive integers(正整数,不为0),and 3x=4y=7z .then what is the minimun value(最小值) of x+y+z?
4）A shop opens at 10:00 am and closes at 6:00 pm.About 100 customers enter into this shop per hour averagely,and about 20 customers will leave the shop per half hour averagely.Then this day,the shop opens at 10:00 am as usual,please count how many customers left in the shop after 9 hours?
5) 17 10又1\4 15又1\4 11又3\4 13又1\2 13又1\4 11又3\4 _____