In the magic square shown, the sums of the numbers in each row, column, and diagonal are the same. Five of these numbers are represented by v, w, x, y, and z. Find y \plus{} z.
<spanclass=′latex−bold′>(A)</span>43<spanclass=′latex−bold′>(B)</span>44<spanclass=′latex−bold′>(C)</span>45<spanclass=′latex−bold′>(D)</span>46<spanclass=′latex−bold′>(E)</span>47
[asy]unitsize(10mm);
defaultpen(linewidth(1pt));
for(int i=0; i<=3; ++i)
{
draw((0,i)--(3,i));
draw((i,0)--(i,3));
}label("25",(0.5,0.5));
label("z",(1.5,0.5));
label("21",(2.5,0.5));
label("18",(0.5,1.5));
label("x",(1.5,1.5));
label("y",(2.5,1.5));
label("v",(0.5,2.5));
label("24",(1.5,2.5));
label("w",(2.5,2.5));[/asy]