The first step to writing a rational number in decimal form is converting the fraction into a mixed number. -18/5 in mixed number form is -3 and 3/5. From this, you can get that the answer is going to be something that starts with a -3. Then you divide 3 by 5 and get 0.6. Put them together and you have -3.6. I hope this helps. I hope you have a wonderful day!!