Answer:
6b is a simpler expression that is equivalent to 4b+2b.
Explanation:
Given : At a library book sale, hardcover books sell for $4 and paperbacks sell for $2.
The expression 4b+2b represents the total cost for b hardcover books and b paperbacks.
We have to write a simpler expression that is equivalent to 4b+2b.
Equivalent expression are expression which are different in seeing but when we solve both we get the values same as the original expression.
Given expression is 4b+2b,
We can take 2b common from terms to get an equivalent expression as,
4b+2b = 2b(2+1) = 2b(3) = 6b.
Thus, 6b is a simpler expression that is equivalent to 4b+2b.