3.125 , we can write it as
3 125/1000
3 1/8
25/8
149x15=2235. If there were 8 duds in 149 it averages a dud every 18 firecrackers. So we know there's 2086 more so we for sure know there is more than 10 most likely more than 15 I'm assuming 15-30 so if there are any answers in that range I think it could be the answer (if more than one answer is in that range let me know and I'll try figuring out the exact answer)
so 4/5 of A is really 80% of A then.
since a whole A is 100% of A, 100% - 80% = 20%, A is being reduced by 20%, namely 1/5.
200 x 0.99. Or you can do 200/100 which is 2. then multiply that by 99 which gets you 99 which is 198.