For the line that has a positive slope, the equation is y = 2x - 1
This is because slope is rise over run(rise/run) or m = y₂-y₁ / x₂-x₁. The line goes up(rise) 2 units, and goes to the right(run) by 1 unit.
The y-intercept(the point the line touches when x = 0) is -1.
You use the equation y = mx + b, try to find m and b(y-intercept) and plug it into the equation.
For the line that has a negative slope, the equation is y = -x + 5