Plz help me schools in 2 more days

So, to begin, we can set the scenario into an equation to solve for the amount of magnets that Sarah had...
Joseph had 28 magnets, plus an unknown amount, x :
28 + x
Sarah had 157, plus the same unknown amount.
157 + x
Also, Sarah had four times the amount of Joseph at the end:
4(28 + x)
As a full equation:
[tex] 157 + x = 4(28 + x) [/tex]
Now, all we have to do is solve for x, the unknown amount:
[tex] 157 + x = 4(28 + x) [/tex]
Use the Distributive Property on 4(28 + x):
[tex] 157 + x = 112 + 4x [/tex]
Subtract x on both sides:
[tex] 157 + x - x = 112 + 4x - x [/tex]
[tex] 157 = 112 + 3x [/tex]
Subtract 112 on both sides:
[tex] 157 - 112 = 112 - 112 + 3x [/tex]
[tex] 45 = 3x [/tex]
Divide by 3 on both sides:
[tex] 15 = x [/tex]
15 is the unknown amount added to each pile of magnets!
Hope I could help you out!
Have a good one, and God bless!