Your first match
You've seen li and blr. One more fact ties them together: r3 is where a function's return value lives. So a function that just returns a constant has almost nothing to do — load the constant into r3, then blr.
li r3, 7 # put the constant 7 in r3
blr # return
In C, that's just:
int answer(void) {
return 7;
}
Your task
For the exercise we've changed the value, so yours won't be a 7. Check the Target asm and write the C. Hit Compile & Check (or ⌘/Ctrl + Enter) to see how you did.