How am I supposed to do this Polynomial Question?!

(7a^5-3a^3+5) - (-2a^5-4a^3+13)

I have tried it multiple getting the same wrong answer.

Sean mows lawns in the summer. He charges the same fixed amount for each lawn that he mows. As of today, he has earned $36 after mowing 3 lawns. a.

John has 4 dozen cans of soda that are 16 oz each . How many 12 oz cups will he need to hold all of the soda

In a factory that manufactures tires, a machine responsible for molding the tire has a failure rate of 0.2%.

A company packs boxes at a constant rate of 3/4 of a box every of a box every 1/2 minute. What is the number of boxes per A company packs boxes at a constant rate of minute the company packs?

Solve and explain your "Math Thinking" 12-7

Solve each problem. Determine which choice (or choices) best represent the equation: 10 is 5 times as many as 2 (A) 5 + 5 = 10 B. 5 * 5 = 10 C. 5 x 2 = 10 D. 10 = 2 x 5

Evaluate the expression for x = 4 1/3 9x + 4 A) 39 B) 40 C) 43 D) 52

Tom rented a truck for one day. There was a base fee of $16.99, and there was an additional charge of 90 cents for each mile driven. Tom had to pay $190.69 when he returned the truck. For how many miles did he drive the truck?

What are the advantages of using an algebraic expression to represent a pattern rule, compared with describing the pattern in words?

What is they ratio of students in 6th grade if there are 20 6th graders and 24 students in 5th grade