Why is transmittance generally considered a more accurate measurement than absorbance

Both the terms form the basis subject of spectrometry and are dependent on each other for various reasons.

Absorption cannot be easily measured and requires laser based technologies to perform the task while transmittance can easily be measured with the help of instruments.

The value of absorption is usually low and relatively less than 1 while the value of transmittance is usually high.

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4