calculează
a) 3+3×[3+3÷3×(3+3×3)]
b)812-4×[6×(61-3600÷12÷30)]÷9
c)[214+240÷(16-2×5)]×25-25÷25
d)90+7×[1614-12000÷(18-10)]-16
e)44+8[280÷(37)]÷32-7
f)(18×8+56)÷[50×40÷(220-2×60)]​