I have seen those touchscreen somewhere. It is possible that those resistors connect together in the middel of the screen. The wires come from the midpoints of the screen edges. Let's say you connect left and bottom to ground and right and top to +5V and the resistors are 500 ohm. Touching the center will give a left-right and top bottom value of 500.
+y
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-x ----O---- +x
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-y
Something like that. A pure analog thing. You can read the values with the analog inputs