求PREP-DS-2-80解

yuletide9

（1）和（2）分别代入计算~

顺便问下~

Prep 数学破解哪里有下啊？~~

感激

jesuisdesole

80.   7589-!-item-!-187;#058&005492

If x and y are positive integers such that x = 8y + 12, what is the greatest common divisor of x and y ?

 

(1) x = 12u, where u is an integer.

 

(2) y = 12z, where z is an integer.

搞不清楚怎么算，答案是B

请高手指点，谢谢