Sarah used
18 of the string to tie some presents. She threw away
310 of the remaining string. As a result, she had 931 cm of the string left. How much string did Sarah have at first? Give your answer in cm.
Fraction of the string left after tying some presents
= 1 -
18=
78 Fraction of the remaining string left after throwing away
= 1 -
310=
710
Fraction of the total string left
=
78 ×
710=
4980
Length of the string at first = 80 u
Length of the string left = 49 u
49 u = 931
1 u = 931 ÷ 49 = 19
Length of the string at first
= 80 u
= 80 x 19
= 1520 cm
Answer(s): 1520 cm