((Please help :D)) All the books at a store have the same price. The store is having a sale advertised with “buy one book, get the second half off.”
a) Write an expression with two terms to represent the cost of buying two books during the sale.
b) Write an equivalent expression with only one term.

Part A

Let x be the cost of one book (before any kind of discount is applied). The first book is x dollars. The second book will be x/2 dollars since we get the second book half off. This is another way of saying a discount of 50%. We can write x/2 as (1/2)x or 0.5x; so there are multiple ways to answer. Probably the easiest to write out would be 0.5x

From here, we add the two costs x and 0.5x to get x+0.5x

We do not combine like terms, as that will happen with part B

Part B

We'll use the result of part A.

Think of the first x as 1x. It's saying we have one copy of x

So x+0.5x is the same as 1x+0.5x

Then to combine like terms, we add the numbers 1 and 0.5 to get 1.5

So 1x+0.5x = 1.5x

We can use the distributive property to see that

1x+0.5x = (1+0.5)x = 1.5x

Or you can think of it like saying "we have one x and half an x added, so overall we have one and a half x's"

However method you use, the answer from part A combines to 1.5x

If you want a fraction form, then it would be (3/2)x since 3/2 = 1.5; though I find decimals to be easier to work with.