Question 548253
={{{12/20-8/30}}}
={{{cross(12)/cross(20)-cross(8)/cross(30)}}}
={{{3/5-4/15}}}
Take LCD
={{{((3)(3)-(4)(1))/15}}}
={{{(9-4)/15}}}
={{{5/15}}}
={{{cross(5)/cross(15)}}}
={{{1/3}}}