Cost of 1.5 litres of milk = Rs. 35 Cost of 1 litre of milk = 35/1.5 = Rs. 70/3 By Alligation, 
Thus, quantity of water to be added = 2 × (60/5) = 24 litres
There are 3 series, you have to find value of a, b, c and then establish relation among a,b,c.
19, 25, 45, a, 553, 2767
1560 760 360 160 6...
35 36 40 49 65 ?
...22 15 10 20 33 93.5
...299, 302, 308, 317, ?, 344
7, 8, 12, 21, 37, ?
1335 737 355 141 47 ?
...? + (55)2= (140)2– (80)2– 6278
148, ‘?’ , 15 4 , 17 8 , 23 8 , 35 8 , 56 8
94 282 284 852 856 2562
...123 125 129 132 ? 145
