Find the prime factorization
45=3*3*5
60=2*2*3*5
GCF=3*5=15
45=3*15
60=4*15
remember
ab+ac=a(b+c) so
45+60=15(3)+15(4)=15(3+4)=15(7)=105
I have seen you ask this question twice before, so I will give you the answer that HugoD gave you:
In mathematics, "of" is translated as a multiplication.
So, you have :

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36000 lbs = 16329.325 kg
18 ton = 18000kg
18 ton is greater
11°F is what the temperature was at 5:00 a.m.