What is the value of x in the triangle

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?

Me find the answers and explain the process to find the answer of the problem appreciate it : )

At the beginning of? 2007, a? start-up company had already received 60 comma 00060,000 hits at its website. at the beginning of? 2009, that number had climbed to 430 comma 000430,000. calculate the rate at which the number of hits is increasing.