Question 913484
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Hi,
*[illustration rectangular_solid.png].

Surface = 2Lw(top and bottom) + 2Lh(long sides) + 2wh(short sides)
Lw = 60, L ={{{ 60/w}}}
Lh = 120, h = 120/L , h = {{{120/(60/w)}}}
wh = 72 , {{{120w/(60/w) = 72}}}, w^2 = 60*72/120 = 36, w = 6cm
w = 6c m, L = 10cm{{{60/6}}}, h = 12cm{{{120/(60/6)}}}