first you add 3d to d so you gonna have 4d and after that you can add 7 on both sides so you gonna have : 4d = 25/4 + 7 ⇒ 4d = 25/4 + 28/4 ⇒ 4d = 53/4 now you can multiply the both sides by 1/4 so you gonna have : d = 53/16 ⇒ d = 3.31 :)) i hope this is helpful have a nice day
