Sorry, I'm just using my phone right now. But I can answer that.
When it says ³ , you should multiply it three times by itself.
So in (x+5)³ , multiply x+5 three times by itself
(x+5)(x+5)(x+5)
= (x²+10x+25)(x+5)
= x³+15x²+75x+125 <--- answer
In (x+2y)³ , you do the same
(x+2y)(x+2y)(x+2y)
= (x²+4xy+4y²)(x+2y)
= x³+6x²y+12xy²+8y³
I hope it can help
