Express the Sum Using Summation Notation $$\frac { 6 } { 7 } + \frac { 7 } { 8 } + \frac { 8 } { 9 } + \frac { 9 } { 10 } + \ldots + \frac { 19 } { 20 }$$

Multiple Choice

Express the sum using summation notation. Use a lower limit of summation, not necessarily 1, and k for the index of
summation.
- $$\frac { 6 } { 7 } + \frac { 7 } { 8 } + \frac { 8 } { 9 } + \frac { 9 } { 10 } + \ldots + \frac { 19 } { 20 }$$

A) $\sum _ { k = 7 } ^ { 19 } \frac { k } { k + 1 }$
B) $\sum _ { k = 7 } ^ { 19 } \frac { k + 1 } { k }$
C) $\sum _ { k = 6 } ^ { 19 } \frac { k } { k + 1 }$
D) $\sum _ { \mathrm { k } = 6 } ^ { 19 } \frac { \mathrm { k } + 1 } { \mathrm { k } }$