He/she idk, got a higher score on the second test. How you do it is divide the score by the number out of it so like 19 divided by 25. Umm for the ratio, I'm not really sure, I guess you just do 19:25 and 17:20
Just plug in a calculator 336/7 and you should get a non decimal answer.
The slope-intercept form:

m - slope
b - y-intercept
We have the slope 
and point (9, 7). Substitute:

<em>subtract 3 from both sides</em>

Answer: 