Dmitry B. answered • 04/18/20
Five years of Prealgebra tutoring at a math group
Answer: 5 * (11 + 7), because
55 + 35 = 90
and
5 * 11 + 5 * 7 = 90
so, 55 + 35 is the same as 5 * (11 + 7).
How did I get 5 * (11 + 7) in the first place?
I factored in my mind both composite numbers into their primes:
55 = 11 * 5
35 = 7 * 5
And used a common prime factor 5 over a distributed property.
Now all operations I did above are based on fundamental math principles. For example, factoring is based on the fundamental theorem of arithmetic. A distributed property, for example, you can easily see in action if you just draw a rectangle. This way you will understand what this is all about. Understanding is a key here, If you don't understand things, but just memorize rules and formulas, this is a total waste, no matter what others tell you.
