To solve sin(55) = x/18, you just need to get x by itself, which gives you about 14.74. Since x is being divided by 18, you can clear that by multiplying both sides by 18. That changes the whole thing into x = 18/sin(55). From there, just type sin(55) into your calculator, just check that it's set to degrees and not radians, and you'll get a decimal around 0.8192. Then multiply that decimal by 18, and you'll end up with 14.7447, which rounds off to 14.74.