Mesmos valores do professor, só iniciei o retângulo verde nas coordenadas (0, 0). :)
<meta charset = "UTF-8">
<canvas width="600" height="400"> </canvas>
<script>
var tela = document.querySelector("canvas");
var pincel = tela.getContext("2d");
pincel.fillStyle = "darkgreen";
pincel.fillRect(0, 0, 350, 300);
pincel.fillStyle = "black";
pincel.fillRect(50, 60, 90, 90);
pincel.fillRect(210, 60, 90, 90);
pincel.fillRect(140, 150, 70, 100);
pincel.fillRect(100, 190, 40, 110);
pincel.fillRect(210, 190, 40, 110);
</script>