I can't see the whole problem
a geometric sequence is a bunch of numbers where you can get from a number to the next number by multiplying the previous number by a certain number
might be confusing so here's an example
1,2,4,8,16
each term is multiplied by 2 to get next term, that number that each term is multiplied by is called the common ratio
formula for geometric sequence is

where
is nth term
is first term
r is teh common ratio
n=which term
in our example
1,3, 9, 27, 81
each term is being multiplied by 3 so it is a geometric sequence and thus r=3
also first term is 1 so 
so the formula is
or in function notation 
Try adding a picture next time maybe...?
Answer:
y = 2.5x
Step-by-step explanation:
y = mx + b
m=2.5 (slope) --> y=2.5x+b
coordinate : (2,5) 2 is the x coordinate, 5 is the y coordinate
to Find b, input the coordinate --> 5 = 2.5(2) + b
5 = 5 + b
0=b
y= 2.5x
This is only since it asked to solve using the point. If you look at the graph, the line intercepts the y-axis at (0,0) so b=0.
hope this helps