Problem: tim came second in math . when his mother asked him how much he had scored , he answered that he got the sum of the first 9 even numbers . his mother immediately worked out the answer . how much had he scored in math ?
Rationale: "b 90 sum = ( n x n ) + n hence , 9 x 9 = 81 + 9 = 90"
annotated_formula: multiply(add(9, const_1), 9)