Well of course the values in $a get captured when the assignment is made. What do you think was going to happen?

for (my $i=1; $i <= $hoeveel; $i++) {
   $y = $y + 155;
   $z = $z +1;
   print <<EOT;
 <g
     transform="translate(-124.85653,$y)"
     id="layer$z">
    <text
       xml:space="preserve"
       style="font-style:normal;font-variant:normal;font-weight:normal
+;font-stretch:normal;font-size:126.0375061px;line-height:125%;font-fa
+mily:Arial;-inkscape-font-specification:'Arial, Normal';text-align:st
+art;letter-spacing:0px;word-spacing:0px;writing-mode:lr-tb;text-ancho
+r:start;fill:#000000;fill-opacity:1;stroke:none;stroke-width:1px;stro
+ke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
       x="-45.714272"
       y="235.21936"
       id="text3336"><tspan
         id="tspan3338"
         x="-45.714272"
         y="235.21936">a</tspan></text>
  </g>

EOT
};
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