Three angles, \[x=3{{(p+25)}^{o}},\,\,y=(p-20)\] and \[z={{(2p+35)}^{o}}\] are on a straight line. Find the value of p.

• A.  \[{{60}^{o}}\]                                
• B.  \[{{30}^{o}}\]        
• C.  \[{{30}^{o}}\]                    
• D.       \[{{15}^{o}}\]