What is the 22nd term in the arithmetic sequence in which a4 is 73 and a10 is -11?

 For A.P nth term's formula is 
An=a1+(n-1)d 

5.) a4=31, a10=85 
put n=4 into general term (given above) 
a4=a1+(4-1)d 
31=a1+3d (putting values of a4) 
a1=31-3d > (1) 

Now put n=10 
a10=a1+(10-1)d 
85=31-3d+9d (putting values of a10, and a1) 
85=31+6d 
6d=85-31 
6d=54 
d=54/6 
d=9 

Now put the value of 'd' into eq (1) 

a1=31-3d 
a1=31-3(9) 
a1=31-27 
a1=4 

Thus the series will be 
a2=a1+d=4+9=13 
a3=a2+d=13+9=22 
and so on 

4,13,22, 

And the same process for your second question 

Answer is negative 2