Comparison: Sara has three times as many pencil erasers as Sam together they have 28 erasers how many erasers does Sara have

You can do this problem algebraically by assigning variables. If Sara has 3 times Sam we can say Sam is x and Sara is 3x and together they have 28.

Which looks like

3x + x = 28

4x = 28 (divide both side by 4)

x = 7

So Sara have 3x which after substitution or replacement looks like this

3 x 7 = 21.

So Sara have 21 pencil eraser.

Sara has 21

Sam has 7

7x3 = 21 + sams 7 = 28