The equation that the question is asking to expand the (x+3)^6 using Pascal's triangle and base on my further computation and further calculation, I would say that the answer would be (x+y)6 = 1⋅x6y+6⋅x5y1+15⋅x4y2+20⋅x3y3+15⋅x2y4+6⋅x1y5+1⋅xy6, I hope you are satisfied with my answer and feel free to ask for more
