Question

How do you do the work for

$43 dinner; 18% gratuity

Answer 1

The total cost of the dinner with gratuity is $50.74Add the gratuity to the regular price.  Method 2: Add the percent of gratuity to 100%. 100% + 18% = 118% The total cost is 118% of the bill.  Method 1: Add gratuity to the regular price. Find the gratuity. 

Answer 2

Start by calculating just the gratuity by itself. We know its 18% of $43. Another way to write 18% is 0.18 so:
$G= 43 \times 0.18$
$G= 7.74$

So just the gratuity by itself is $7.74. If you want to know the entire bill you can add up the meal and the gratutiy like so

$T= Meal + Gratuity$
$T = 43 + 7.74 = 50.74$

Another way to do it is to recognize that you are paying for 100% of the meal and then paying antoher 18% AGAIN for a total of 118% or 1.18. If you do this you get the same answer:

$43 \times 1.18 = 50.74$