i tried and im stuck, just tell me the answer to the first one

The answer to your first practice question is 0.15 mm. This lesson on hole standards explains that a screw needs room to pass, and 0.15 mm per side—which adds up to 0.3 mm on the diameter—is the absolute minimum clearance you can use. If you go any tighter than that, the joint stops acting like a clamped joint and starts acting like a pin in a hole, which causes binding and slop 26.

This 0.15 mm per side clearance is the honest floor because it has to absorb several real-world factors at once. According to this lesson's breakdown, it accounts for drill cutting errors, position errors when stacking parts, fastener thread runout, and everyday obstructions like paint, anodizing, or burrs 2.