Multiply the cost by 1.2 (120%) to add 20% tip, and then multiply by 0.85 (85%) to take off 15%
78.96 x 1.2 x 0.85 = 80.54
The function

is a parabola concave up, whose solutions are

from here, you can use the quadratic formula

to find that the solutions of the parabola are 
So, the parabola is positive if
(which wouldn't make sense in our case) or 
So, if Tanya caters 25 meals she breaks even, and starting with the 26th meal she will begin to profit.
Answer:
<h2>y = 2</h2>
Step-by-step explanation:

Not really Specific in asking in what way you want it answered... So here is what Im able to understand.
Function
Joseph : 20 + .23x = y
Micki : 10 + .15x =y
Hope this is what your asking...
The LCM of 15 and 6 is 30
5x6
12x2