To find area $ A $ use formula:
$$ A = \frac{ a^2 \sqrt{3}}{2} + 3 a l $$After substituting $ a = 4 $ and $ l = 10 $ we have:
$$ A = \frac{ 4^2 \sqrt{3}}{2} + 3 \cdot 4 \cdot 10 $$$$ A = \frac{ 16 \sqrt{3}}{2} + 3 \cdot 40 $$$$ A = \frac{ 16 \sqrt{ 3 }}{2} + 120 $$$$ A = 8 \sqrt{ 3 } + 120 $$$$ A = 133.8564 $$