how many term are in the sequence of multiples of 7 between 100 and 900

They would be 7, 14, 21, ... , 896

this is an AP, where a = 7, d = 7, term(n) = 896
a+(n-1)d = term(n)
7 + (n-1)(7) = 896
7 + 7n - 7 = 896
n = 128 , so there are 128 terms