namely, let's rationalize the denominator in the fraction, for which case we'll be using the <u>conjugate</u> of that denominator, so we'll multiply top and bottom by its <u>conjugate</u>.
so the denominator is 5 + i, simply enough, its conjugate is just 5 - i, recall that same/same = 1, thus (5-i)/(5-i) = 1, and any expression multiplied by 1 is just itself, so we're not really changing the fraction per se.

Ok so if 1200 total pens and 60 were taken that's a ratio of 1200/60=20
out of 60pens 4 didn't work, again ratio is 4/60=1/15 so about 1/15 of the pens didn't work.
so we have 1200pens * 1/15broken ratio = 80 pens or we can say
20*4=80pens won't work from 20 groups of 60 and 4 out of 60 not working is 20*4=80 not working from total batch of 1200.
hope this helps you some! thank you!!!!!!!!!
<span>x2 − 8x + 16
= (x - 4)(x - 4)
= (x - 4)^2</span>