10. No
6/15=0.4 while 15/40=0.375
11. X=1.0822
Multiply the left side by 4.5/4.5 and the right side by 2.7/2.7. The equation you will get is 4.5x/12.15=4.87/12.15. Multiply both sides by 12.15. Your equation will now be 4.5x=4.87. Solve both sides for x by dividing both sides by 4.5.