20. (6 points) Observe the calculation patterns of the following equations:
First row $1+2+3=6$
Second row $3+5+7=15$
Third row $5+8+11=24$
$\qquad$
The equation in the twelfth row is $\qquad$
【Answer】Solution: According to the analysis, the first addend of the twelfth row's equation is $2 \times 12-1=23$, the second addend is $3 \times 12-1=35$, and the third addend is $4 \times 12-1=47$. Therefore, the equation for the twelfth row is $23+35+47=105$. Hence, the answer is: $23+35+47=105$.