Question 916428
the slab :
{{{W=15ft}}}, {{{L=10ft}}, and {{{h=6in}}} 

Concrete is usually sold by the {{{cubic}}} {{{ yard}}}.

first convert everything in {{{ yards}}}

{{{1Foot = 0.333Yards}}}
{{{1Inch = 0.02778Yards }}}

 
{{{W=15ft}}}=> {{{W=15*0.333Yd}}}=> {{{W= 4.999Yd }}}
{{{L=10ft}} =>{{{W=10*0.333Yd}}}=> {{{W= 3.333Yd }}} 
{{{h=6in}}} =>{{{h=6*0.02778 Yd}}} =>{{{h= 0.16667yd }}}


volume:

{{{V=L*W*h}}}

{{{V=3.333Yd*4.999Yd *0.16667yd}}}

{{{V=2.777yd^3}}}  

Bob will need for the slab {{{2.777yd^3}}} of concrete.