At Kenji's Swimwear, 30% of the 70 swimsuit styles are bikinis. How many bikini styles are there?

My

21  bikini styles

Step-by-step explanation/math I took to do the problem:

30 ÷ 100 x 70

right

step-by-step explanation:

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