From Danny, there are 3 * 10 = <<3*10=30>>30 watermelon slices

From his sister, there are 1 * 15 = <<1*15=15>>15 watermelon slices

There are a total of 30 + 15 = <<30+15=45>>45 watermelon slices

# Answer

45
<|im_start|>system
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<|im_start|>user
Danny brings 3 watermelons to his family picnic. He cuts each watermelon into 10 slices. His sister brings 1 watermelon to the family picnic, and she cuts the watermelon into 15 slices. How many watermelon slices are there in total at the picnic?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
45
Danny brings 3 watermelons to his family picnic. He cuts each watermelon into 10 slices. His sister brings 1 watermelon to the family picnic, and she cuts the watermelon into 15 slices. How many watermelon slices are there in total at the picnic?
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