Here is the equation:

Since both decimals are negative, the answer will be positive.
- Negative times Negative = Positive
Divide both sides by -3.9 to leave the variable alone:

r is equal to 4 → r = 4
Answer:
@Genius102 has answered this already, but here it is
Step-by-step explanation:
a) the scale should go by 1,000 because that would show that the slope is growing by time.
b) the intervals should go by 500 because 18,500 is the last number, so it should be 500
Well you will say 17.8÷3.9=17.8×10÷3.9×10=178÷39=4.56410256410256 rounded to the nearest hundreds is 4.56.