Answer: y=4
Explanation:
There are different ways to solve this problem. One is to know how functions work, and the other is to create a function and plug in x=1. In this case, we are lucky that they gave us a point where x=1. The point is (1,4).
Knowing a function, you plug in an x and output a y. In the point (1,4), you are inputting 1 and outputting 4.
This is the same things as saying f(1)=y, or f(1)=4. Therefore, the value is y=4.