Taking sum of rows

Question

I need to find the total score. I tried using mutate but its not working. I want the total score for each school. rowSums() does not work. It shows an error : 'x' must be numeric

scores_final = scores_final %>% mutate(total_score = sum(Math_score,Eng_score,Science_score)) 

school name   no_of_test_takers    Math_score   Eng_score  Science_score
abc                 4                  34          22          33
def                 20                 44          55          77
ghi                 33                 45          67          44