First add the numbers together:
-13+(-5),6,(-7),9=-10
Then divide that number by the total # of numbers, which is 5
-10÷5=-2
The average low temperature is -2.
...which is 6th grade stuff, so I am having a hard time believing, that you are in college and/or are having problems with this.
If both triangles are similar the ratio of sides will be same

6 goes into 64 ten times with a remainder of 4
you know that
- 300
- 59
- 4
- 78
ok so put it like that and it will be correct.............................................................................(long pause)........................................................................................................... (thinks) I think that the right answer.