单选题If 2x + 5y = 8 and 3x = 2y, what is the value of 2x + y?
单选题A school supply store sells only one kind of desk and one kind of chair，at a uniform cost per desk or per that of 1 desk and 3 chairs．then the total cost Of 4 desks and 1 chair is how many times that
单选题Bowls X and Y each contained exactly 2 jelly beans， each of which was either red or black．One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y， After the exchange．were
单选题The cardinality of a finite set is the number of elements in the set．What is the cardinality of set A? 1 2 is the cardinality of exactly 6 subsets of set A． 2 Set A has a total of 16 subsets．including
单选题In order to reduce dependence on imported oil,
单选题If kSn is defined to be the product of n + kn - k + 1 for all positive integers k and n, which of the following expressions represents k + 1Sn+1 +1?
单选题100个连续自然数按从小到大的顺序排列的和为8450，取出其中第1个，第3个，…，第99个，再把剩下的数相加，和为多少?
单选题Which of the following most logically completes
单选题Is the perimeter of triangle ABC greater than 20?1BC-AC=102the area of tangle ABC is 20.
单选题If 1 2
单选题The use of growth-promoting antibiotics in hog
单选题For over two centuries, no one had been able to
单选题A computer equipped with signature-recognition
单选题Budget constraints have made police officials
单选题某电子设备厂生产的计算器有25％是不合格的，910不合格的计算器被检验出来后扔掉；并且有15合格的计算器被错误地扔掉。假设所有未扔掉的计算器都被出售，该电子设备厂出售的计算器中有百分之几是不合格的?
单选题Urban planner: When a city loses population due
单选题An “Armstrong number” is an n-digit number that is equal to the sum of the nth powers of its individual digits．For example，153 is an Armstrong number because it has 3 digits and 13+53+33=153．What is t
单选题There were 36，000 hardback copies of a certain novel sold before the paperback version was issued． From the time the first paperback copy was sold until the last copy of the novel was sold，9 times as