Write an algebraic expression for product of 10 and the sum of x and 8

That would be the same as : 10 * (x + 8)

Okay, so it's asking for the product of 10, and the sum of 8 and k. Sum is the answer to an addition problem, so that would make the last of it 8 + k. And we'd be multiplying this with 10, so that would make it : 10 * (x + 8)