The jayden family eats at a restaurant that is having a 15% discount promotion. their meal costs $78.65, and they leave a 20% tip. if the tip applies to the cost of the meal before the discount, what is the total cost of the meal?

$82.58

Step-by-step explanation:

78.65×0.85=66.85

0.2×78.65=15.73

66.85+15.73=82.58

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204