The 38 degree angle and the (6x +4) angle are supplementary which means both have to add up to 180 degrees. 180 - 38 leaves us with 142. When you plug in 23 to x you get (6(23) + 4) 6 times 23 is 138 and 138 plus 4 is 142. Which gives us our answer of x = 23.
