After using
18 of her sugar, Mrs Oh bought another 20 kg of sugar. As a result, Mrs Oh now has
128 as much sugar as what she had at first. How many kilograms of sugar did Mrs Oh have at first?
|
Sugar |
Total |
Before |
8 u |
8 u |
Change 1 |
- 1 u |
|
After 1 |
7 u |
|
Change 2 |
+ 20 |
|
After 2 |
7 u + 20 |
12 u |
Fraction of sugar left after using
18 of it
= 1 -
18 =
78 Amount of sugar left after using some = 7 u
Amount of sugar after buying 20 kg of sugar = 7 u + 20
7 u + 20 = 12 u
12 u - 7 u = 20
5 u = 20
1 u = 20 ÷ 5 = 4
Amount of sugar that Mrs Oh had at first
= 8 u
= 8 x 4
= 32 kg
Answer(s): 32 kg