The sum of the first 4 terms of a linear sequence (A.P) is 26 and that of the next 4 terms is 74, find the values of the first term and the common difference.
4a + 6d = 26 ... 8a + 12d = 52
8a + 28d = 100
subtracting equations ... 16d = 48
solve for d , then substitute back to find a