(3 \times 5) \times 2 = 3 \times ({}(3×5)×2=3×(left parenthesis, 3, times, 5, right parenthesis, times, 2, equals, 3, times, left parenthesis{} \times 2)×2)

Aplane travels 1000 miles in 5 hours .what is the planes average speed?

Idon’t quite understand this problem

Photoelectrons with a maximum speed of 6.50 x 107 m/s are ejected from a surface in the presence of light with a frequency of 6.75 x 1014hz. if the mass of an electron is 9.10 x 10-31 kg, calculate in joules the maximum kinetic energy of a single electron. 3.84 x 10-15 j 1.92 x 10-15 j 5.92 x 10-23 j 3.07 x 10-16 j