Explain how you could determine whether the seeds in a packet of round pea seeds have the genotype Rr or RR, in which R represents round seeds and r represents wrinkled seeds?

Assuming R indicates dominant and r indicates recessive, I don't know how you could determine the genotype. Are there a combination of both genotypes in the packet, or just one? If they are solely Rr, about 25% of the next generation would be rr, wrinkled seeds.