Question
Risa used 16 of the thread to tie some presents. She threw away 310 of the remaining thread. As a result, she had 21 cm of the thread left. How much thread did Risa have at first? Give your answer in cm.
4 m

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Risa used 16 of the thread to tie some presents. She threw away 310 of the remaining thread. As a result, she had 21 cm of the thread left. How much thread did Risa have at first? Give your answer in cm.