How do you subtract to find the sum of a positive and negative integer

positive integer subtraction 8-9= -1

negative integer subtraction -8-(-9) but before you can subtract you have to distribute the negative sign so now your problem looks like -8+9 because a negative times a negative equals a positive and now your answer is 1

i leave the calculator work to you.

7. diameter 4 miles, circumference 4π miles

8. radius 0.2 miles, circumference 0.4π miles

[this is a bad problem because the actual radius of a car on the track is less than 0.2 miles so the answer is less than 0.4π miles]

9. radius 6 feet, circumference 12π feet

10. diameter 14 cm, circumference 14π cm

11. diameter 4.8 feet, circumference 4.8π feet

hi,

6x times 4 is 24x and 5 times 4 is 20, so the answer is 24x+20.

hope this and for a little humor i am groot.