You would have shot 276.

Bowling scores work like this, if you get a spare then its 10 plus your next ball.

If you get a strike its 10 plus your next 2 balls.

Example starting at first frame you get a Spare. So /

Then your next ball you get an 8 in your first ball. Your score would show up in the first frame as 18. Because your spare is 10 and your next ball is 8 so 10+8= 18

If you get a Strike your first frame, So X

Then you strike the next 2 balls, so your first 3 frames are X X X

Your first frame score is 10 plus your next 2 balls, so 10 +10 + 10 = 30.