6. Antun has $80 \%$ more stickers than Branko. Branko has $\frac{3}{5}$ of the number of stickers that Darko has. If Branko gave 150 stickers to Darko, then Darko would have 3 times more stickers than Branko. How many stickers do all three of them have together?
First method:

If the number of stickers Darko has is denoted by $x$, then Branko has $\frac{3}{5} x$ stickers.

1 POINT

If Branko were to give 150 stickers to Darko, then Darko would have $x+150$ stickers, and Branko would be left with $\frac{3}{5} x-150$ stickers.

2 POINTS

Darko would then have 3 times more stickers than Branko, so the equation $3 \cdot\left(\frac{3}{5} x-150\right)=x+150$ holds. $\quad 1$ POINT
$\frac{9}{5} x-450=x+150$

$\frac{4}{5} x=600$

2 POINTS

$x=750$

Darko has 750 stickers, and Branko has $\frac{3}{5} \cdot 750=450$.

1 POINT

Antun has $80 \%$ more than Branko, so $1.8 \cdot 450=810$.

2 POINTS

Together, they have $750+450+810=2010$ stickers.

1 POINT

TOTAL 10 POINTS