NN看下这两道PS的题

xihongshi7_7

1.If n is an integer, which of the following CANNOT be a factor of 3n+4?
A 4 B 5 C 6 D 7 E 8 我觉得没有答案

2.In Township K, 1/5 of the housing units are equipped with cable television. If 1/10 of the housing units, including 1/3 of those that are equipped with cable television, are equipped with videocassette recorders, what fraction of the housing units have neither cable television nor videocassette recorders?
A 23/30 B 11/15 C 7/10 D 1/6 E 2/15
答案给的是A，我怎么说都是B啊，是不是答案给错了？