Answer:
In mathematics, an expression or mathematical expression is a finite combination of symbols that is well-formed according to rules that depend on the context.
Step-by-step explanation:
Mathematical symbols can designate numbers (constants), variables, operations, functions, brackets, punctuation, and grouping to help determine order of operations, and other aspects of logical syntax. Many authors distinguish an expression from a formula, the former denoting a mathematical object, and the latter denoting a statement about mathematical objects.
P=2(l+w)
Substitute width plus 3 for length
Remember order of operations: multiply before adding
86=2((w+3) + w)
86=2w+6+2w
86=4w+6
80=4w
20=w
23=w+3=l
Check the answer
86=2((w+3) + w)
86=2((20+3)+20
86=2(23+20)
86=46+40
86=86
You can divide by the same number every time
