15,15,
15,15. (1)三对数都能使方程两边的值相等.将三组数带到方程即可. (2)解方程即可:x=10, y=-1是方程的解.16. (1)y=(22-5x)/3, (2)任意三个x=1,y=17/3; x=2, y=4; x=3, y=7/3 (3)非负整数两对x=2,y=4; x=4,y=2.