A $7-$in$.$ thick flat$-$plate slab with spans of $20ft$ in each direction is supported on

a$)16$ in$.x16$ in$.$ columns.

b$)10$ in$.x24$ in$.$ columns.

The average effective depth is $5\mathrm{.}6in.$ Assume the slab supports its own dead load, plus $25$ psf superimposed dead load and $40$ psf live load. The concrete strength is $4000$ psf$.$ Check one$-$way and two$-$way shear at a typical interior support. Assume unbalanced moments are negligible.