Correct Answer - C
According to question,
`(angleABC)/(angleACB) = 5/1` , `(angleBAC)/(angleACB) = 3/1`
`therefore angleABC=180^(@)-120^(@)`
`angleABC=60^(@)`
`angleACB= 180^(@)-105^(@)`
`angleACB=180^(@)-105^(@)`
`angleACB=75^(@)`
`therefore angleABC+angleACB+angleBAC=180^(@)`
`angleBAC=180^(@)-75^(@)-60^(@)`
`angleBAC=45^(@)`