Assume That Investigators Crossed a Strain of Flies Carrying the Dominant

Assume that investigators crossed a strain of flies carrying the dominant eye mutation Lobe on the second chromosome with a strain homozygous for the second chromosome recessive mutations smooth abdomen and straw body.The F₁ Lobe females were then backcrossed with homozygous smooth abdomen,straw-body males,and the following phenotypes were observed:
smooth abdomen,straw body 820
Lobe $\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$ 780
smooth abdomen,Lobe $\quad$$\quad$ 42
straw body $\quad$$\quad$$\quad$$\quad$$\quad$$\quad$ 58
smooth abdomen $\quad$$\quad$$\quad$$\quad$ 148
Lobe,straw body $\quad$$\quad$$\quad$$\quad$ 152
(a)Give the gene order and map units for these three loci.
(b)What is the coefficient of coincidence?