The Planck–Einstein relation

gives that E, the photon energy, is equal to h, Planck's constant, times <span>ν</span>, the frequency.
We can solve the equation in terms of frequency to get

We substitute our given energy,

, and Planck's constant,

.
30$ originally - 21$ paid = 9$ discount
> divide the discount by the original price, multiply by 100 to get the percent decrease.
100 x (9$ / 30$) = 30% discount
> So the shoes where on sale for 30% off the original price.
for the equation:
100 x (30-21)/30 = % decrease
Answer:
volume = 160 cubic units
Step-by-step explanation:
volume = (6 x 4 x 5) + (4 x 2 x 5) = 160 cubic units