The measure of angle 1 is (3x + 10) and the measure of what is the measure of angle 7?
angle 4 is (4x - 15).
2 4
1 3
6/8
5 7

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value

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

the answer should be a. snail