Erika used
15 of the thread to tie some presents. She threw away
56 of the remaining thread. As a result, she had 20 cm of the thread left. How much thread did Erika have at first? Give your answer in cm.
Fraction of the thread left after tying some presents
= 1 -
15=
45 Fraction of the remaining thread left after throwing away
= 1 -
56=
16
Fraction of the total thread left
=
45 ×
16=
215
Length of the thread at first = 15 u
Length of the thread left = 2 u
2 u = 20
1 u = 20 ÷ 2 = 10
Length of the thread at first
= 15 u
= 15 x 10
= 150 cm
Answer(s): 150 cm