The table shows the results of randomly selecting colored marbles from a bag 40 times. The marble was returned to the bag after each selection. A: 0.125
B: 0.20
C: 0.80
D: 1.0

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons

place r′ so that qr′ is parallel to the tangent.

now we get that ∠r′py=∠pr′q, where y is on the tangent, on the opposite side of p from x.

also, because of the symmetry, ∠r′py=∠qpx.

finally, note that no matter where we place r, as long as it's on the correct arc, we have ∠prq=∠pr′q.

stringing all these equalities together, we end up with ∠prq=∠qpx.

this picture will show how its going to look like.

hope this by jack monhen

is there more info provided? there is not enough information given in the problem