[6x (4 - 2) + (21 x $ +1)] ÷ 3^2 54 ÷ 6 + 0.4^2 x (9 x 8 ÷ 2 + 8^2)

I really don't get this.
Please help

The production line where you work can assemble 5 appliers every 30 minutes at this rate how long should it take the line to assemble 125 amplifiers

Find the solution on the interval [0, 2pi)

90.0% complete a b c d e confirm last week, your delivery runs took 7 hours 12 minutes on monday, 6 hours 46 minutes on wednesday, and 6 hours 53 minutes on friday. what was your average time for a delivery run?