Figure out what your 5RM max or estimate it if you are a good estimator and do 6 sets of 3 with your 5RM. If you under or overestimate, you can adjust accordingly the next time (lower or raise the weight you are using)
The second, 2 x 24, with your 26RM max should be in the ballpark of about 50% of your 1RM.
Basically, it will leave you with a couple of reps in the tank for both set schemes.