i have to use slope for % error

here is the graph ans the table, i am trying to calculate percent error but my number is way too high idk what i did wrong the slope of the graph is suppose to be my expimental g but i guess its to high, pleaseeee help these values are the same for all trials, i.e keep initial position the same for all trials in the table below, distance traveled will remain the same, and the angle will increase**