The high temperatures for the first five days in December were as follows: 28°, 3°, -2°, -4°, and 12°. What is the average high temperature of the five days? If the next day is 0°, would the average of the six days increase or decrease?

yo answer should be 6 if im not mistaken

step-by-step explanation:

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