Answer:
The second, the fourth and the final.
Explanation:
With the first: 4c = 41.5 => c=83/8 ? (c isn't 1.5: incorrect)
With the second: 150:c=100 =>c=150:100=1.5 (correct)
With the third: 13.5-c=10 => c=13.5+10=23.5 (incorrect)
With the fourth: 6c=9 => c=9:6=1.5 (correct)
With the final: 0.2c=0.3 => c=1.5 (correct)