slope is just "how much up or down" for one step to the right.
its clearly negative here
only -3 seems to be remotely plausible looking at the graph in your screenshot
Answer:
see below!!
Step-by-step explanation:
x + 3y = 5,
y = –x + 3
Substitute the point into each equation and verify that it is true
x + 3y = 5, 2 +3(1) = 5 5 = 5 true
y = -x +3 1 = -2+3 1=1 true
(2,1) is a solution
This doesn’t make sense
You say 28 did biology, but then 15 did maths and biology, and 16 did physics and biology
15 + 16 is 31 ??

Cross multiply:

Divide by h on both sides: