Genetic question?

Well the problem tells you that 2 double flowered plants are crossed. Ask yourself what kind of genotype (don't be concerned with crossing yet) is needed to have a double flowered plant. You only have two options DD or Dd (dd you have a singled flowered plant). Now try doing some Punnett squares using either DDxDD or DDxDd or DdxDd and see which one gives you a ratio similar to 17:6