Answer:
-4 < x ≤ 9
Step-by-step explanation:
I believe the shirts are different (in color, in size, in style,...), is so then:
¹⁰C₆ = (10! )/( 6! )( 10-6) ! = 210 COMBBINATIONS
Given that: step 1

step 2: subtract 3x both side

Step 3: Add 18 both side:

Step 4: divide both side by 5

Step:6 The value of x is:
x=6
well, we know the "sum" of both angles is 90°, notice the rectangle in the corner, so we can say that the angles are simply complementary angles, thus

Plug
into the equation of the ellipsoid:

Complete the square:

Then the intersection is such that


which resembles the equation of a circle, and suggests a parameterization is polar-like coordinates. Let



(Attached is a plot of the two surfaces and the intersection; red for the positive root
, blue for the negative)