To solve for c, get rid of the denominator, then move all the parts containing c to one side, then factor out c:
tan55=(c+4)/c
tan55color(blue)(*c)=(c+4)/(c)color(blue)(*c)
tan55color(blue)(*c)=(c+4)/color(red)cancelcolor(black)(c)color(blue)(*color(red)cancelcolor(blue)c)
ctan55=c+4
ctan55-c=4
c(tan55-1)=4
color(blue)(color(black)(c(tan55-1))/(tan55-1))=color(blue)(color(black)4/(tan55-1))
color(blue)(color(black)(c color(red)cancelcolor(black)((tan55-1)))/color(red)cancelcolor(blue)(tan55-1))=color(blue)(color(black)4/(tan55-1))
c=color(blue)(color(black)4/(tan55-1))
color(white)c~~9.3425636...
That's the solution. Hope this helped!