A metal alloy weighing one KG and containing 10% iron is melted and mixed with three KG of a different lawyer which contains 90% iron what percent of the resulting alloy is iron

Explanation:

A = {1,2,3}

B = {2,3,5}

A u B = {1,2,3,5}

The set A u B consists of anything in either set A or set B. This is a set union.

The complement of this is the complete opposite. So we only consider the items 4 & 6

(A u B)' = {4,6}

Note that sets AuB and (AuB)' can be unioned together to end up with the universal set U. Be sure not to mix up the universal set notation U with the union symbol 'u'

The last step is to see what sets (AuB)' and set C have in common. That would be 4 and 6 since both values are found in both sets

Therefore, (A u B)' n C = {4, 6}

The n refers to the intersection symbol.