Question 541013
Area = Lenght x Width

Area of field:

{{{ A = 210 * 330}}}

{{{ A = 69300 m^2}}}

Area of barn

{{{A= 29*45}}}
{{{A = 1305 m^2}}}

Then 

Field - Barn = Area left

{{{69300 - 1305 =  67995 m^2}}}