7. Five contestants $A, B, C, D, E$ participate in the "The Voice" competition, and the five of them stand in a row for a group appearance. They each have a contestant number on their chest, and the sum of the five numbers is 35. It is known that the sum of the numbers of the contestants standing to the right of $\mathrm{E}$ is 13; the sum of the numbers of the contestants standing to the right of $D$ is 31; the sum of the numbers of the contestants standing to the right of $A$ is 21; the sum of the numbers of the contestants standing to the right of $C$ is 7. What is the sum of the numbers of the contestants standing at the far left and the far right? $\qquad$
【Answer】 11
【Analysis】According to the problem, $D$ is on the far left, so $D=35-31=4, B$ is on the far right, so $B=7,7+4=11$.