What is the answer to this f(x)3x+7=

There really isn't a answer. Let me explain, this is a function. A function shows what operation you have to do to get a y value or any kind of value. Whenever it has a f(x) or any variable in the 'x' part you will automatically know that it's a function. So what you do is substitute any number for the variable that's there, any number, whether it's 100 or 1. So in this case a x is what we have to put in a substitute for. So let's try 1. 1x3 = 3, 3+7 is 10. So the function of x for 1 is 10. Now keep doing that and you'll get numbers which will turn into points in a graph (when we substituted in a 1 and got a result that's the y value) and that's the "answer".