Question

i need some help please

Answer 1

@Hero

Answer 2

Are you supposed to write the entire proof in the box?

Answer 3

i dont think so

Answer 4

@Hero ?

Answer 5

So what exactly are you supposed to write in the box then?

Answer 6

the missing proof i guess

Answer 7

Ah, I'm just now seeing the second pic you posted. Hang on

Answer 8

Well, I know the answer, but I can't outright give it to you. I'll give you a hint though. Suppose you have an equation $x + 3 = 4$ and you know $x = 1$. what can you do with the 1?

Answer 9

substitute x?

Answer 10

Yes and that's your hint.

Answer 11

so it's substitution?

Answer 12

Correct.