Ernie earned $121.50 more than kaylin. tria earned $35 less than 3 times the amount kaylin earned. ernie, tria, and kaylin earned $579 in all. how much did tria earn?

X - Ernie, y - Kaylin, z - Tria
x = y + 121.50
z = 3y - 35
x + y + z = 579

z = 3 y - 35      =>   - 3 y + z = -35
y + 121.50 + y + z = 579

- 3 y + z = - 35        / · ( -1 )
 2 y + z = 457.50     (we will use the elimination method) 

3 y - z = 35
2 y + z = 457.50

5 y = 492.5,            y = 492.5 : 5 = 98.5
z = 3 · 98.5 - 35
z = 260.5
Tria earned $260.5