what is the difference between a number sentence and an expression?

Answer 1

A neumber sentence has an equal sign, and is a sentence as long as it holds true
ex true:3+7=10
False: 13+1=15
an expession does not have an equal sign
ex: 3+4/5*3

Answer 2

Make a true sentence by inserting parentheses.4x9-2=28

Answer 3

4 x (9-2) = 28