-1

According to the slope formula: Slope = \(\displaystyle\frac{{{y}_{2}-{y}_{1}}}{{{x}_{2}-{x}_{1}}}\)

\(y_2 = 6.1\)

\(y_1 = 3.1\)

\(x_2 = -5.5\)

\(x_1 = -2.5\)

Therefore: \(\displaystyle{6.1}-\frac{{3.1}}{{-{{5.5}}}}--{2.5}\)

Since negative negative is positive you are left with: 3/-3

Therefore the answer is -1.