Since this is a right triangle we can use the law of cosine (adjacent/hypotenuse) to solve. You get the equation cos(49)=x/55. You then wanna multiply 55 to both sides so you can isolate x. You get 55*cos(49)=x. Then, you put 55*cos(49) into a calculator and multiply to get 16.5325899059.... Then round to the nearest hundredth to get 16.53 as your answer.
Hope this helps :) (its been a while since I've done trig ratios so thanks for the refresher)