Can someone answer all these questions for me?

Suppose a man is heterozygous for heterochromia, an autosomal dominant disorder which causes two different‑colored eyes in an individual, produced 25‑offspring with his normal‑eyed wife. of their children, 15 were heterochromatic and 10 were‑normal. calculate the chi‑square value for this observation.

Ineed i been stuck on this question since yesterday

Write the percent as a fraction or mixed number in simplest form. 0.8%