Algebra help please!?

Here's my equation; 3a^2 -13a=10 I understand the next step, -10 from both sides to get to here; 3a^2-13a-10=0. Now the mml software has a "Help me Solve this" button and when I click on that it shows me this; 3a^2-13a-10=0 (3a+2)(?) I don't understand where... show more Here's my equation; 3a^2 -13a=10 I understand the next step, -10 from both sides to get to here;
3a^2-13a-10=0. Now the mml software has a "Help me Solve this" button and when I click on that it shows me this; 3a^2-13a-10=0
(3a+2)(?)

I don't understand where the +2 comes from or know what to do in order to fill in the ?.
Can someone please explain what I need to be doing here, I know I have to factor the 10 right, so my solution set should either be {2, 5} or {1, 10} or am I just way off here? Please help!
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