Solve for a. Round to the nearest tenth, if necessary.

Answer:
Step-by-step explanation:
tanx=12/18
x=arctan(12/18)
tan(90-x)=12/(a+5)
tan(90-arctan(12/18)=12/(a+5)
a+5=12/tan(90-arctan(12/18))
a=12/tan(90-arctan(12/18))-5
a=3