说90% of students learn either Geography or A(单词不认识-。-!),and 15% lean both, if learn G is the 2 times the percent of the peole learn A, what is the percent learn G but not A. 选项35%,65%,50%。
(提供者ID:dcrh86。狗主选的是50%) 思路:
A+G+B=90%
B=15%
G+B=2(A+B)èG=2A+B
求G.
A+G=90%-15%=75%èA=75%-G
G=2A+B=2(75%-G)+15%è3G=165%èG=55%
我的思路是:题目说的either A or G ,所以我的式子是: 只A+只G=90% 2(只A+15%)=只G+15% 求出只G=65% 请指教啊!!!!!!!