7x + 3 (3x+6) = 194 what is the answer

What is the missing step in this proof ?

You were told that the amount of time lapsed between consecutive trades on the new york stock exchange followed a normal distribution with a mean of 15 seconds. you were also told that the probability that the time lapsed between two consecutive trades to fall between 16 to 17 seconds was 13%. the probability that the time lapsed between two consecutive trades would fall below 13 seconds was 7%. what is the probability that the time lapsed between two consecutive trades will be between 14 and 15 seconds?

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?