Question 658547
Assuming the rectangular box is closed and has 6 sides, the surface area would be:
a = 2*l*w + 2*w*h + 2*h*l, so
{{{1020 = 2*6*9 + 2*9*h + 2*h*6}}}
{{{1020 = 108 + 18*h + 12*h}}}
{{{18*h + 12*h = 1020 - 108}}}
{{{30*h = 912}}}
{{{h = 912/30 = 30&12/30 = 30&4/10 = 30.4}}} inches

However, this isn't the correct answer.  So our initial assumption that the box is closed must be wrong.  If the box is open at the top and has only a bottom and 4 sides, the surface area is
a = l*w + 2*w*h + 2*h*l, so
{{{1020 = 6*9 + 2*9*h + 2*h*6}}}
{{{1020 = 54 + 18*h + 12*h}}}
{{{18*h + 12*h = 1020 - 54}}}
{{{30*h = 966}}}
{{{h = 966/30 = 32&6/30 = 32&1/5 = 32.2}}} inches