first you need to get all like term on one side of the equal sign, so you would do that by adding 5 to both sides of the equal sign which would give you 2c-5+5=c+4+5 the (-5) and +5 cancel out so now your equation should look like this 2c=c+4+5 which = 2c=c+9 now you need to get c on the other side of the equal sign so since c is positive we do the opposite again and subtract c from both sides which gives you an equation that looks like this 2c-c=c-c+9 which = 1c=9 or you want to get c by itself so you do the opposite again so instead of multiplying c by 1 you'd divide it by 1 but you have to divide both sides by 1 which gives you 1c/1=9/1 = c=9 so your answer is c=9