Sigma Notation and Arithmetic sequences

Evaluate the sum given the following: $a_1=5,\ a_n=25,\ n=11$  

Evaluate the sum given the following: $a_1=12,\ a_n=34,\ n=12$  

Evaluate the sum given the following: $5,\ 14,\ 23,...\ n=11$  

Evaluate the sum given the following: $29,\ 39,\ 49,\ ...\ n=20$  

Evaluate the sum given the following: $\sum_{n=1}^7n$  

Evaluate the sum given the following: $\sum_{n=1}^7n^2$  

Evaluate the sum given the following: $\sum_{n=5}^{10}n^2$  

Evaluate the sum given the following: $\sum_{n=1}^6100-n^2$  

Find the 21st term in the arithmetic sequence given: $a_{13}=41,\ \ a_{34}=83$