Question

Sari has 3 times as many pencil erasers as Sam. Together, they have 28 erasers. How many erasers does Sari have?

Answer 1

she has 25 erasers.
28
- 3
-----
25

Answer 2

Let

x--------> amount of erasers that Sari has

y--------> amount of erasers that Sam has

we know that

`x=3y`-------> equation
`1`

`x+y=28`-----> equation
`2`

Substitute equation
`1` in equation
`2`

`[3y]+y=28\\ 4y=28\\ y=28/4\\ y=7`

find the value of x

`x=3y\\ x=3*7\\ x=21`

therefore

the answer is

Sari has
`21` erasers