(3/8) x + 1/3 = 7/12, (note use PEMDAS parenthesis, Exponent, M ultiplication, Division, Addition, Subtraction first) 3/8 = 0.375, 1/3 = 0.333, 7/12 = 0.5833, then substiture everything in the equation. there we will have.. (0.375) x + 0.333 = 0.5833. transpose 0.333 to the other side then it will be... (0.375) x = 0.5833-0.333 (note: the sign of the numbers will be different when transposing.) then we will have (0.375) x / 0.375 = 0.2503/ 0.375, divide both sides with .375 to cancel the value so the X will only remain. the equation now will be x=0.2503/0.375, x= 0.667