Alright because of P.E.M.D.A.S we want to start with the paranthesis but there is nothing we can do so we move on to exponents.
4^2 is 16
16(20-×)-8(x+3)=8 we need to distribute the numbers in front of the paranthesis across both number inside them.
320-16x-8x-24=8
now combine like terms
296-24x=8
now we need to isolate the variable so subtract 296 from both sides.
-24x=-288
now divide both sides by -24
x= 12