Can you show the problem? Those are the questions but I need the actual graph.
The answer to your question is 2 and 4.
let h= history books
science books = s
h=2s there are 2 times as many history as science so to get them equal we double the science
h+s=81 there are 81 total history and science books
2s+s=81 substitute 2s for h in the above equation
3s = 81 combine like terms
s = 27
There are 27 science books
h=2s
h=2(27)
h=54
there are 54 history books
A)


b)
since QR=QP, that means that QO is an angle bisector, and thus the segments it makes at the bottom of RO and OP, are also equal, thus RO=OP
thus, since the point P is 0.5 units away from the 0, point R is also 0.5 units away from 0 as well, however, is on the negative side, thus R (-0.5, 0)
c)
what's the equation of a line that passes through the points (-0.5, 0) and (0,2)?

Answer:
40
Step-by-step explanation:
why ? because the total angle measure in triangle is 180degree so we have a right angled triangle so 90+50 = 140
180-140 = 40
hope it's correct