You are already given the poverty percentage which is 54%. All you have to do is substitute it to the equation to calculate the predicted score.
Predicted Score = 71 - 0.61*54
Predicted Score = 38.06
About the predicted score of the residual, I guess you use the other percentage which is 100 - 54 = 46%. I'm not sure what the median value is for.
Predicted Score = 71 - 0.61*46
Predicted Score = 42.94