Answer
33 cans of paint are needed.
Work Step by Step
We can find the semi-perimeter $S$:
$S = \frac{75+68+85}{2} = 114$
We can find the area:
$A = \sqrt{S~(S-a)(S-b)(S-c)}$
$A = \sqrt{(114)~(114-75)(114-68)(114-85)}$
$A = \sqrt{(114)~(39)(46)(29)}$
$A = \sqrt{5,930,964}$
$A = 2435.36~m^2$
We can find the number of cans of paint which are required:
$\frac{2435.36~m^2}{75~m^2} = 32.5~cans$
Therefore, 33 cans of paint are needed.
