Give me answerr fast plzz

Hint: It an A.G.P series, so find its sum consider the sum of given series as S – (1), Then multiply the given series by common ratio i.e. (1/4) and shift all the number by one place in right and then subtract the resultant series from the equation (1) , by doing this you will get the G.P. then you can easily simplify and get the value of d = 9.

Thanks. Vijay