提问几道GRE绿皮数学题P58The toll for a certain bridge is $0.15 or 1 token.Tokens are sold in packs of 40 for $4.00.The percenty save on 40 trips across the bridge if a token,rather than $0.15,is used to pay ea
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P58 Tokens are sold in packs of 40 for $4.00 意思是团购的话每个token 0.1 $ ,前面说The toll for a certain bridge is $0.15 or 1 token.意思是单买的话每个token 0.15 $ ,所以买40个token剩下的钱的百分比是 (40*0.15 - 4)/4=0.5 =50%