Answer
The result is\[{{414}_{\text{seven}}}\].
Work Step by Step
To subtract numerals of the same base other than base ten, if the upper number is larger than a lower number then subtract normally. But if the upper number is smaller than a lower number then borrow base value from the previous number.
Here, upper number \[2\]is smaller than a lower number \[5\]. So, borrow \[1\]from \[6\]. Now this one is equal to base size which is \[7\]. Add \[7+2=9\]and subtract normally \[9-5=4\]
\[\begin{align}
& \underline{\begin{align}
& 5\overset{5}{\mathop{{}}}\,{{\overset{9}{\mathop{{}}}\,}_{\text{seven}}} \\
& -{{145}_{\text{seven}}}
\end{align}} \\
& \text{ }4
\end{align}\]
Now, subtract other digits in the same manner:
\[\begin{align}
& \underline{\begin{align}
& \text{ }5\overset{5}{\mathop{{}}}\,{{\overset{9}{\mathop{{}}}\,}_{\text{seven}}} \\
& -1\text{ }4\text{ }{{5}_{\text{seven}}}
\end{align}} \\
& \text{ }{{414}_{\text{seven}}}
\end{align}\]
Hence, the result is\[{{414}_{\text{seven}}}\].
