Sarah used
17 of the thread to tie some presents. She threw away
79 of the remaining thread. As a result, she had 16 cm of the thread left. How much thread did Sarah have at first? Give your answer in cm.
Fraction of the thread left after tying some presents
= 1 -
17=
67 Fraction of the remaining thread left after throwing away
= 1 -
79=
29
Fraction of the total thread left
=
67 ×
29=
421
Length of the thread at first = 21 u
Length of the thread left = 4 u
4 u = 16
1 u = 16 ÷ 4 = 4
Length of the thread at first
= 21 u
= 21 x 4
= 84 cm
Answer(s): 84 cm