In chimpanzees straight fingers are dominant to bent fingers. make a punnett square to show the genotypes and phenotypes expected for the following cross heterozygous straight x heterozygous bent

Heterozygous straight (F) x heterozygous bent (f)

|FF | Ff   |
|Ff  | ff    |

That means 1/4 will be 100% straight
2/4 will have straight with a recessive trait of bent
1/4 will be recessive recessive which means bent

So out of 4 chimpanzees, 1 of them will have bent. 

Hope this is what you wanted help with. :)