A prism has 3 rectangular faces and 2 triangular faces and 2 rectangular faces = 10(3 + 4 + 5) = 120
Area of triangular faces = $\sqrt{s(s-a)(s-b)(s-c)}$
where s = $\frac{a+b+c}{2}$
= $\frac{3+4+5}{2}$
= $\frac{12}{2}$
= 6
Area of $△$ = $\sqrt{6(6-30(6-4)(6-5)}$
= $\sqrt{6\times 3\times 2\times 1}$ = 6
Area of triangle faces = 2 x 6 = 12cm²
Total surface area = Area of rectangular face + Area of $△$ = 120 + 12
= 132cm²