Question

Lian and her younger sister Ella are 4 years apart. The sum of their ages is 20. Let l be Lian’s age in years and let e be Ella’s age in years. The system of linear equations that models the scenario is: l – 4 = e l + e = 20 How old is each sister?

Answer 1

L - 4 = E
L = E + 4
remplace
E + 4 + E = 20
2e =16
e = 16/2
Ella is 8 years old. and given that is 4 years younger. then Lian is 12

Answer 2

Lian is 12 years old and Ella is 8 years old.

Explanation:

Lian and her younger sister Ella are 4 years apart.

The sum of their ages is 20.

Let L be Lian’s age in years.

Let E be Ella’s age in years.

The system of linear equations that models the scenario is:

`L-4=E` this gives
`L=E+4`

`L+E=20`

Putting L=E+4 in the second equation

`E+4+E=20`

`2E=20-4`

`2E=16`

So,
`E=8`

Now we have , L+E=20

`L+8=20`

So,
`L=12`

Therefore, Lian is 12 years old and Ella is 8 years old.