As slope is given m = - 3 and line is passing through point ( - 2, 3).Using slope - intercept form of equation of line, we will find intercept first

y = mx + c ……………….(1)

3 = - 3( - 2) + c

3 = 6 + c

c = 3 - 6

c = - 3

Putting the value of c in equation (1), we have

y = - 3x + ( - 3)

y = - 3x - 3

3x + y + 3 = 0

So, the required equation of line is 3x + y + 3 = 0.