Question 1110492
 
{{{ 6.5 <= p < 7.5 }}}
{{{ 4.5 <= q < 5.5 }}}

i)  Largest value of p+q:    {{{ p + q < 13cm }}}   So p+q can reach up to, but not including, 13cm.

ii)  Smallest value of p+q:   {{{   p+q  >= 11cm }}}    p+q can be as small as 11cm.

iii)  Largest possible value of p-q:  That will occur when p is maximum and q is minimum.   
                                              {{{    p-q  < 7.5-4.5 }}} —>  {{{ p-q < 3  }}}  —>  p-q can be  up to, but not including, 3cm.  

iv)  You can do the last one.   You're only supposed to ask one question per post, and I've already answered three.