Just find the y intercept for both lines and calculate the change in y with respect to the x axis, aka slope. You can write an equation from any line by doing what I just said. The y-intercept is the y value where the function intercepts the y-axis.
Red Line:
Y-intercept = 2
Slope = 1/1
Blue Line:
Y-intercept = 4
Slope = -1/2
And you should know the equation, atleast I hope you do.
y = mx + b
m being the slope
b being the y-intercept
You now got:
y = x + 2
and
y = -(1/2)x + 4
Make them equal to each other since they are both equal to y. Solve for x and then solve for the actual y value. I don’t want to do everything for you, since you wouldn’t really learn anything