Evaluate the following numerical expressions.
a. 2 × 5 + 3 × 2 + 4

b. 2 × (5 + 3 × 2 + 4)
30
c. 2 × 5 + 3 × (2 + 4)

d. 2 × (5 + 3) × 2 + 4

e. (2 × 5) + (3 × 2) + 4

f. 2 × (5 + 3) × (2 + 4)

Can the parentheses in any of these expressions be removed without changing the value of the expression? Explain why or why not.