Can someone plz plz plz help me with this( also the word that is cut off says Then

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.

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

X+ y = 5 ; x - y =3 solve using linear combination