Across is performed between a plant with genotype ttyy and a plant with genotype ttyy. if the two genes independently assort, what is the probability, expressed as a decimal, that the offspring will be homozygous for gene t and homozygous for gene y?

The given question says a cross is performed between two homozygous recessive individual, both having genotype ttyy.

In any case, the gametes produced by these plants would be recessive for the trait and the cross between these individual would always give rise to a homozygous recessive progeny.

Hence, in any case, the progeny would be homozygous for allele t, and allele y.

So, the probability of offspring having homozygous for gene t and homozygous for gene y would be 100% or 1.