87 less than the quotient of an unknown number and 43 is -75

$13.80

Step-by-step explanation:

Let's first figure out how much the tax is in dollars.

We see that Beth will be tipping a value of 15% of her $12 meal. Remember that in math, "of" almost always means to multiply, so we're multiplying 15% by 12:

15% * 12 = 15/100 * 12 = 0.15 * 12 = $1.80

So, the tip is $1.80. Add this to the original $12 to get the total cost:

$1.80 + $12 = $13.80