We know that <span>An electrician can wire a house in ------------> 20 hours so 100%----------------> 20 hours X-------------------> 12 hour x=12*100/20----> x=60%
that means </span><span>the apprentice in 12 hours complete the (100-60)----> 40%
</span>the apprentice in 12 hours complete -------> 40% x hours------------------------------------> 100% x=100*12/40-----> x=30 hours
