Machine M1 & M2 both manufactures product Q at least time.
Maximum number of units can be manufactured by machine M1 in one day is = $\dfrac{{8}*{60}}{6}$ [∵Each machine works 8 hours per day]
= 80
Maximum number of units can be manufactured by machine M2 in one day is = $\dfrac{{8}*{60}}{6}$
= 80
Maximum number of units that can be manufactured in one day by machine M1 * machine M2 = 80 + 80 = 160 units