Because a horizontal line is 180 deg. Use 180 - 70 to get have of DTO Angle deg. DTO = 110 deg. 70 is across 3x -5 The 3x - 5 is opposite of 70 so the angle is also 70 deg. So 3x - 5 = 70
Isolate x Add 5 to both sides of the equation
Should look like this now 3x = 75 Divide by 3 on both sides Now x = 25
To get angle DTO you use supplementary and subtract 70 from 180 and get 10. to get X you see that the angle is 70 and since it's vetical it would equal 70 too so you just mutiply 3×25 and get 75 then subtract 5 and lastly get 70.