Answer:
50%
Step-by-step explanation:
The punnett square cross they show you is between the genotypes Bb and bb. (See the Bb and bb at the top and right?)
Heterozygous means with one dominant gene (uppercase letter, in this case B) and one recessive gene (lowercase letter, in this case b).
The cross is already done for you. The 4 letter combinations that result from the cross of Bb and bb show as: Bb, bb, Bb, and bb. Using what we know, an individual that is heterozygous should have one B and one b (Bb). 2 out of 4 of the crosses are Bb. With basic math, that's then 50%.