1. Find a right triangle having area 5 and rational sides.
2. Same task for area=7.
The "6 is easy" in the title seems to be a reference to the 3-4-5 right triangle which has a area of 6. So if I want an area of 5 just scale the sides by a factor of 5/6: (5/2, 10/3, 25/6); if I want an area of 7 then scale by 7/6: (7/2, 14/3, 35/6).
In fact I don't need the 3-4-5 triangle specifically, any Pythagorean triangle can be used like the 9-40-41 Steve used. So what makes this puzzle a Difficulty 4?