In peas, yellow seeds (y) are dominant to green seeds (y). a homozygous dominant and a homozygous recessive plant are crossed and have two offspring. these two offspring are now crossed with each other. what are the chances that the second generation of offspring (the offspring of the first offspring) will have yellow seeds

You can figure this out by doing a punnet square to figure out the first generation, and then continue with that punnet square into the next generation.

  Y     Y

y Yy  Yy

y Yy  Yy
It is 100% guaranteed that the first generation is going to be heterozygous dominant. Now we take this and do a second punnet square 

     Y    y
Y  YY  Yy

y   Yy   yy

The second generation has a 75% chance of having yellow seeds.
I hope that this helps!