Question 825028
x = the angle
( 90 - x ) = the complement
( 180 - x ) = the supplement
13:4 = ( 180 - x ):( 90 - x )
or
{{{(13/4) = (( 180 - x )/( 90 - x ))}}}
do the cross products
{{{4( 180 - x )=13( 90 - x )}}}
720 - 4x = 1170 - 13x
add 13x to each side
720 + 9x = 1170
subtract 720 from each side
 9x = 450
divide each side by 9
  x = 50