Greg owns a clothing store where he designs T-shirts, t, and pairs of shorts, S.

He sells the T-shirts for $6 each and the shorts for $14. Greg can work 18

hours a day, at most. It takes him 30 minutes to design a T-shirt and an hour

and 30 minutes to design a pair of shorts. He must design at least 10 items

each day, but he cannot design more than 25 items in one day. Which set of

inequalities below represents this scenario?

O

A. S 2 10+ t, ss 25+ t, 1.55 s 36 -0.5t, s 2 0; t2 0

O

B. Ss 10-t, s 2 25- t S S 36-t s 2 0; +2 0

O

C. s 2 10-t, ss 25-t, s 2 36-t, s 2 0;12 0

D. S 2 10- tss 25 - 1, 0.5t + 1.58 < 18; s 2 0; 120

The allotropes of carbon include a variety of structures that include three-dimensional tetrahedral lattices, planes of hexagonal rings, cylindrical tubes of hexagonal rings, and spheres of five- and six-membered rings. similar shapes of network covalent atomic solids are possible with carbon nitride, boron, and pure silicon (e.g., silicene is a graphene-like allotrope of pure silicon). in contrast, silicates exist as either highly ordered or amorphous (more random) three-dimensional lattices. what could explain why there are there no naturally occurring sheets, stacked sheets, cylindrical tubes, or spheres of network covalent atomic solids composed of silicon and oxygen (sio2)? would pure silicate structures make good lubricants or good electrical conductors?