1/5 7/12 1/20 We can make the common denominator 60
12/60 35/60 3/60
So these three parts of his week take up 50/60 or 5/6 of his time. That means he only has 1/6 left. The question also tells us after all of this he only has 10 hours left, so 1/6 = 10 hours. If you have 1/6 of something how do you find one whole? or 6/6. You multiply it by 6. so 10*6 = 60, which means every week he works 60 hours.
Similarity implies correspondence. Angles are listed in the order in which they are congruent to one another. A is congruent to I, B is congruent to J, C is congruent to K, D is congruent to L.