请问两题pp2的题目—Q176&Q199

176.

In 1995 Division A of Company X had 4,850 customers. If there were 86 service errors in Division A that year, what was the service-error rate, in number of service errors per 100 customers, for Division B of Company X in 1995 ?

(1) In 1995 the overall service-error rate for Divisions A and B combined was 1.5 service errors per 100 customers.

(2) In 1995 Division B had 9,350 customers, none of whom were customers of Division A.

ANS:A

看不懂A选项
            COMBINE 的意思@@

199.

Warehouse W's revenue from the sale of sofas was what percent greater this year than it was last year?

(1) Warehouse W sold 10 percent more sofas this year than it did last year.

(2) Warehouse W's selling price per sofa was $30 greater this year than it was last year.

ANS:E

想请问what percent greater this year than last year

的数学式是: 今年Sale-去年sale/今年sale 吗???

还是除以去年sale??

感谢~