Hhhhmmmmm...
13.50 for food
2.40 for drink
Since there is a voucher for 1/3 of food,
13.50 multiplied by 1/3 is 4.5 which is the discount
13.50-4.5=9
9 is the final cost for the food.
Add 9 to 2.40 for the drink which results in a total of 11.40
To find the amount charged for service you multiply 11.40 by .15
11.40 × .15 = 1.71
You add 1.71 to 11.40
The total is 13.11
B= Exactly one solution
-6y+9y= 3y
3y+13=8y-3
3y=8y-16
-5y=-16
Let's say that B makes $100.
Then A makes $75.
So, your question then becomes 100 is what percent of 75?
This can be solved by setting up the proportion 100 / 75 = x / 100
75x = 10000
x = 133.3
So, B's income is 33.3% more than A's income.
Answer: You might need to be more descriptive, there's a lot of numbers that could be added together to equal -8.
-4 + -4 = -8.
-6 + -2 = -8.
etc.