The ratio of Harry's stamps to Ronnie's stamps was 6 to 1. Harry gave half of his stamps to Ronnie. He added his remaining stamps and found that he now had 11 fewer stamps than Ronnie. How many stamps did Harry have at first?

Ronnie had R stamps at first

Harry had 6R

After Harry gave 1/2 of his stamps to Ronnie

(1/2) * 6R + 11 = R + (1/2) (6R)

3R + 11 = R + 3R

3R + 11 = 4R

11 = 4R - 3R

11 = R

Harry had 6*11 = 66 stamps at first