Answer:
-9
Step-by-step explanation:it is 2.5 diffrence for each place on the graph so 2.5 times 30 (cause 60 and 90 have a 30 point diffrence) would give you 75 and seince the numbers are decresing to the right side i subtracted 75 from 66 and the awnser is -9. hope this helps and sorry my spelling is bad