the points are (2.1, -6.3) (-2.5, 4.7)
y=mx+b
find what m= and what b =
i got m=-2.39 but the I tried to plug the coordinates into y=mx+b but keep getting two different answers of -1.281 and -1.275.
Both answers for b are correct,correct to three significant figures.
If you had kept more significant figures for m, you would have got -1.2782... as the value of b, which is more or less the average of your two results.