a) To find x in the equation x + 5 = 196, we can subtract 5 from both sides of the equation:
x + 5 - 5 = 196 - 5
x = 191

b) To find x in the equation 6x - 30 = 12, we can add 30 to both sides of the equation and then divide by 6:
6x - 30 + 30 = 12 + 30
6x = 42
x = 42/6
x = 7

c) To find x in the equation 255 - (x + 1) = 45, we can subtract 255 from both sides of the equation and then add 1 to both sides:
255 - (x + 1) - 255 = 45 - 255
-x - 1 = -210
-x = -210 + 1
-x = -209
x = 209

For the second question:
To find the sum S = 1 + 2 + 3 + ... + 98 + 99, we can use the formula for the sum of an arithmetic series:
S = (n/2)(a + l)
where n is the number of terms, a is the first term, and l is the last term.

In this case, n = 99 (since there are 99 terms), a = 1, and l = 99.

S = (99/2)(1 + 99)
S = (99/2)(100)
S = 99 * 50
S = 4950

Therefore, the sum S is equal to 4950.