A student’s monthly savings form an arithmetic progression. The first month’s saving is Rs a and the common difference is Rs d. At the end of 12 months, his saving in the 12th month is Rs 1,750 and the total savings for the 12 months is Rs 15,000. Which of the following pairs of equations correctly represent these two facts?
(a) a+11d=1750,6(a+11d)=15000
(b) a+12d=1750,6(2a+11d)=15000
(c) a+11d=1750,6(2a+11d)=15000
(d) a+11d=1750,12(2a+11d)=15000