Answer:
25%
Explanation:
crossing two heterozygous plants would look like this Pp x Pp
making a chart
           P   p
P Â Â Â Â Â Â Â PP Â Â Â Â Pp
p       Pp      pp
what this means is that the capital P isdminant so thats what will show is the dominant purple petal whereas lower case p is the ressecive white petal
this means 25% of offspring will be white :)