Please help me!!
Really fast please

55%

Step-by-step explanation:

We can infer a few things here and come to a logical conclusion.

$9 is not exactly half of 20 right?

So this tells us that our answer needs to be over 50% because a 50% discount would make the bookbag $10.

If we look at the answers only 1 of them is over 50% and that is 55%.

However, let's check our work

First we multiply 20 by .55 (when multiplying a percent we move the decimal over twice)

We got 11 out of this, the next thing we do is subtract that 11 from the overall 20:

Therefore we see that 55% is the answer!

Hope this helps!!

- Kay

0.02

step-by-step explanation:

time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 k (but other seconds are sometimes used in astronomy)