请教sas base 123 中2题, 谢谢.

16 data work.empsalary;
set work.people(in=inemp);
work.money(in=insal);
if insal and inemp;
run;
The data set work.people has 5 obs, and the data set work.money has 7
observations.
How many obs will the data set work.empsalary contain?
A.0
B.5
C.7
D.12

Why the answer is A.
The default value for inemp and insal is 0?

73.
data work.test;
First='Ipswich, England';
City_Country=substr(First,1,7)!!','!!'England';
run;
Which one of the following is the length of the variable City_Country in the
output data set?
A.6
B.7
C.17
D.25
Why the answer is 25.