For each $t ≥ 2$, show that a $t$-regular Ramsey graph has $$r(3,t+1) ≥ 3t$$
I'm stuck on where to go with this question. I've tried using what few theorems I know, but I've gotten caught up with inequalities that are not helping with anything, such as $r(3,t+1)≤r(3,t)+r(2,t+1)=r(3,t)+t+1$.