404 is the answer. if you add them all together
21/100 is a fraction form
Answer:0.369 m
Step-by-step explanation:
Given
Distance between slit and screen is 
Wavelength 
Angle between zeroth order bright fringe and Fourth-order bright fringe is 
let distance between the slits be d
Distance of n th bright fringe From central Fringe is given by

Also 



y = (2/3)x + 6
because the slope stays the same because it is parallel and to get the y intercept you plug in -3 for x into the equation (2/3)x +? =4 and ?=6 so that gives you the equation y = (2/3)x + 6