This is an addition problem because we want to know how many cups of food Jessica's dog gets altogether in a day. When we put things together we are adding. 

We can start at $\displaystyle 2$ and count up $\displaystyle 1$.

$\displaystyle 2,3$

Then we can count up $\displaystyle 3$.

$\displaystyle 3,4,5,6$

$\displaystyle \frac{\begin{array}[b]{r}2\\ 1\\+\ 3\end{array}}{ \ \ \ \space 6}$

This is an addition problem because we want to know the total number of steps in Cindy's house when we put all three sets of steps together. When we put things together we are adding. 

We can start at $\displaystyle 2$ and count up $\displaystyle 12$.

$\displaystyle 2,3,4,5,6,7,8,9,10,11,12,13,14$

Then we can count up $\displaystyle 6$.

$\displaystyle 14,15,16,17,18,19,20$

$\displaystyle \frac{\begin{array}[b]{r}2\\12\\+\ \ 6\end{array}}{ \ \ \ \space 20}$

This is an addition problem because we want to know how many total minutes Joe spent cleaning altogether. When we put things together we are adding. 

We can start at $\displaystyle 5$ and count up $\displaystyle 7$.

$\displaystyle 5,6,7,8,9,10,11,12$

Then we can count up $\displaystyle 2$.

$\displaystyle 12,13,14$

$\displaystyle \frac{\begin{array}[b]{r}5\\ 7\\+\ 2\end{array}}{ \ \ \space 14}$

This is an addition problem because we want to know how many hotdogs we ate altogether. When we put things together we are adding. 

We can start at $\displaystyle 3$ and count up $\displaystyle 2$.

$\displaystyle 3,4,5$

Then we can count up $\displaystyle 3$.

$\displaystyle 5,6,7,8$

$\displaystyle \frac{\begin{array}[b]{r}3\\ 2\\+\ 3\end{array}}{ \ \ \ \space 8}$

This is an addition problem because we want to know how many cakes are at the cake walk altogether. When we put things together we are adding. 

We can start at $\displaystyle 3$ and count up $\displaystyle 2$.

$\displaystyle 3,4,5$

Then we can count up $\displaystyle 2$.

$\displaystyle 5,6,7$

$\displaystyle \frac{\begin{array}[b]{r}3\\ 2\\+\ 2\end{array}}{ \ \ \ \space 7}$

This is an addition problem because we want to know how many total pizzas we have when we put the pizzas altogether. When we put things together we are adding. 

We can start at $\displaystyle 6$ and count up $\displaystyle 3$.

$\displaystyle 6,7,8,9$

Then we can count up $\displaystyle 7$.

$\displaystyle 9,10,11,12,13,14,15,16$

$\displaystyle \frac{\begin{array}[b]{r}6\\ 3\\+\ 7\end{array}}{ \ \ \space 16}$

This is an addition problem because we want to know how many total supplies Lauren has in her backpack when we put everything together. When we put things together we are adding. 

We can start at $\displaystyle 3$ and count up $\displaystyle 2$.

$\displaystyle 3,4,5$

Then we can count up $\displaystyle 4$.

$\displaystyle 5,6,7,8,9$

$\displaystyle \frac{\begin{array}[b]{r}3\\ 2\\+\ 4\end{array}}{ \ \ \ \space 9}$

In this series we are adding $\displaystyle 2$ each time, or counting by $\displaystyle 2$. $\displaystyle 2+2=4$, $\displaystyle 4+2=6$, $\displaystyle 6+2=8$ and $\displaystyle 8+2=10$

In this series we are adding $\displaystyle 4$ each time, or counting by $\displaystyle 4$. $\displaystyle 4+4=8$, $\displaystyle 8+4=12$, $\displaystyle 12+4=16$, and $\displaystyle 16+4=20$. 

 In this series we are adding $\displaystyle 2$ each time, or counting by $\displaystyle 2$. $\displaystyle 2+2=4$, $\displaystyle 4+2=6$, $\displaystyle 6+2=8$ and $\displaystyle 8+2=10$.