Currently, you have made a
75, 83, and a 78 on your tests in
math. What do you need to
make on the next test in order to
get an average of an 80?

84

Step-by-step explanation:

4 test grades with an average of 80 would have a total of 80x4=320.

75+83+78=236

320-236=84

with btw u said 100pts but it clearly says

i answerd and just got 10pts

no hate

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