What would the answer be, also how do I work it out ?

Answer:
The distance is √58
or 7.61577...
Step-by-step explanation:
If you draw a right triangle where the given line is the hypotenuse you can use Pythagorean theorem (a²+b²=c²) to find the length.
It would be 7 units tall and 3 units wide.
7²+3²=49+9=58
The distance is √58