Question

Mukta had 42 rupees on 4th Jan 2018 season 15 rupees after this day everyday she said 12 more Rupees then the earlier days then including the savings how much total amount that she have up to 30th Jan 2018​

Answer 1

42+15=57

sequence will be

57 69 81

a=57

tn=a+n-1×d

57+27-1×12

t27=369

now put sn formula