### Instruction:
Three congruent isosceles triangles $DAO$, $AOB$ and $OBC$ have $AD=AO=OB=BC=10$ and $AB=DO=OC=12$.  These triangles are arranged to form trapezoid $ABCD$, as shown.  Point $P$ is on side $AB$ so that $OP$ is perpendicular to $AB$.

[asy]
pair A, B, C, D, O, P;
A= (6, 8);
B=(18, 8);
C=(24, 0);
D=(0,0);
O=(12,0);
P=(12,8);
draw(A--B--C--D--A);
draw(A--O--B);
draw(O--P, dashed);
label("A", A, NW);
label("B", B, NE);
label("C", C, SE);
label("D", D, SW);
label("O", O, S);
label("P", P, N);
label("12", (D+O)/2, S);
label("12", (O+C)/2, S);
label("10", (A+D)/2, NW);
label("10", (B+C)/2, NE);
[/asy]

Point $X$ is the midpoint of $AD$ and point $Y$ is the midpoint of $BC$.  When $X$ and $Y$ are joined, the trapezoid is divided into two smaller trapezoids.  The ratio of the area of trapezoid $ABYX$ to the area of trapezoid $XYCD$ in simplified form is $p:q$. Find $p+q$. [asy]
pair A, B, C, D, O, P, X, Y;
A= (6, 8);
B=(18, 8);
C=(24, 0);
D=(0,0);
O=(12,0);
P=(12,8);
X=(A+D)/2;
Y=(B+C)/2;
draw(X--Y, dashed);
draw(A--B--C--D--A);
draw(A--O--B);
draw(O--P, dashed);
label("A", A, NW);
label("B", B, NE);
label("C", C, SE);
label("D", D, SW);
label("O", O, S);
label("P", P, N);
label("X", X, NW);
label("Y", Y, NE);
[/asy]

### Response:

Since $\triangle AOB$ is isosceles with $AO=OB$ and $OP$ is perpendicular to $AB$, point $P$ is the midpoint of $AB$, so $AP=PB=\frac{1}{2}AB=\frac{1}{2}(12)=6$.  By the Pythagorean Theorem, $OP = \sqrt{AO^2 - AP^2}=\sqrt{10^2-6^2}=\sqrt{64}={8}$.

Since $ABCD$ is a trapezoid with height of length 8 ($OP$ is the height of $ABCD$) and parallel sides ($AB$ and $DC$) of length $12$ and $24$, its area is \[ \frac{1}{2}\times\,\mbox{Height}\,\times\,\mbox{Sum of parallel sides} = \frac{1}{2}(8)(12+24)=144. \]

Since $XY$ cuts $AD$ and $BC$ each in half, then it also cuts the height $PO$ in half.
Thus, each of the two smaller trapezoids has height 4.  Next, we find the length of $XY$.  The sum of the areas of trapezoids $ABYX$ and $XYCD$ must equal that of trapezoid $ABCD$.  Therefore, \begin{align*}
\frac{1}{2}(4)(AB+XY)+\frac{1}{2}(4)(XY+DC)&=144\\
2(12+XY)+2(XY+24) & = 144\\
4(XY)& = 72 \\
XY & = 18
\end{align*} Thus, the area of trapezoid $ABYX$ is $\frac{1}{2}(4)(12+18)=60$ and the area of trapezoid $XYCD$ is $\frac{1}{2}(4)(18+24)=84$.
Thus, the ratio of their areas is $60:84=5:7$.
Our answer is then $5+7=12$.