(36 3/4" + 36 3/8" + 371/2" +z) /4 = 36 5/8" This is the equation that you would get for the average. Now we just solve for z. Following PEMDAS you have to mulitply the equation by 4 to get rid of the divide by 4 part. 4( (36 3/4" + 36 3/8" + 371/2" +z) /4 = 36 5/8) Which does this 36 3/4" + 36 3/8" + 371/2" +z = 146 1/2" Now you have to add and subtract to get "z" by itself. 36 3/4" + 36 3/8" + 371/2" = 110 5/8" (110 5/8" + z = 146 1/2" ) -110 5/8" z= 35 7/8", so the answer is b
