$154 is equal to 100%. They way I do it for smaller percents (like 1% -10%) is I find 1% of the number by dividing by 100. In this case, that is $1.54. To find 4%, you multiply that 1% by 4 to get $6.16. By adding that 4% to the 100% you get 104%, or the total price including tax, which is $160.16.
