We have \(\displaystyle 8\) triangles and we want to subtract \(\displaystyle 7\) triangles, which means the same thing as take them away. We can cross off the \(\displaystyle 7\) triangles that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 1\) triangle left. Subtraction is like counting backwards. We can start at \(\displaystyle 8\) and count back \(\displaystyle 7\).

\(\displaystyle 8,7,6,5,4,3,2,1\)

We have \(\displaystyle 8\) triangles and we want to subtract \(\displaystyle 8\) triangles, which means the same thing as take them away. We can cross off the \(\displaystyle 8\) triangles that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 0\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 8\) and count back \(\displaystyle 8\).

\(\displaystyle 8,7,6,5,4,3,2,1,0\)

We have \(\displaystyle 8\) triangles and we want to subtract \(\displaystyle 8\) triangles, which means the same thing as take them away. We can cross off the \(\displaystyle 8\) triangles that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 0\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 8\) and count back \(\displaystyle 8\).

\(\displaystyle 8,7,6,5,4,3,2,1,0\)

To find the difference, you need to subtract. When subtracting, always remember to put the greater number first!  

\(\displaystyle \begin{matrix} &22 \\ - & 14\\ \end{matrix}\)

When we try to subtract the ones place, we will need to cancel. For 22, the ones place becomes 12 and the tens place becomes 1.

\(\displaystyle \begin{matrix} & \ 1\ 12\\ - & 1\ 4\\ & \ \ 8 \end{matrix}\)

The difference between 14 and 22 is 8.

To find the difference, you must subtract.  Line up the numbers vertically. Remember to use the rules of borrowing to subtract:

\(\displaystyle 52.43-36.81=15.62\)

Lucy got \(\displaystyle \$15.62\) back when she returned the t-shirt.

To find the missing piece of an addition problem, we can take the biggest number minus the smallest number. 

\(\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 10\end{array}}{ \ \ \ \ \ \space 1}\)

We can start at \(\displaystyle 11\) and count back \(\displaystyle 10\).

\(\displaystyle 11,10,9,8,7,6,5,4,3,2,1\)

To find the missing piece of an addition problem, we can take the biggest number minus the smallest number. 

\(\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 10\end{array}}{ \ \ \ \ \ \space 2}\)

We can start at \(\displaystyle 12\) and count back \(\displaystyle 10\).

\(\displaystyle 12,11,10,9,8,7,6,5,4,3,2\)

To find the missing piece of an addition problem, we can take the biggest number minus the smallest number. 

\(\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 10\end{array}}{ \ \ \ \ \ \space 3}\)

We can start at \(\displaystyle 13\) and count back \(\displaystyle 10\).

\(\displaystyle 13,12,11,10,9,8,7,6,5,4,3\)

To find the missing piece of an addition problem, we can take the biggest number minus the smallest number. 

\(\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 10\end{array}}{ \ \ \ \ \ \space 4}\)

We can start at \(\displaystyle 14\) and count back \(\displaystyle 10\).

\(\displaystyle 14,13,12,11,10,9,8,7,6,5,4\)

To find the missing piece of an addition problem, we can take the biggest number minus the smallest number. 

\(\displaystyle \frac{\begin{array}[b]{r}15\\ -\ 10\end{array}}{ \ \ \ \ \ \space 5}\)

We can start at \(\displaystyle 15\) and count back \(\displaystyle 10\).

\(\displaystyle 15,14,13,12,11,10,9,8,7,6,5\)