Explain what it is adding or subtracting

Addition is when theres is a certain nuumber of something example 5 apples and there are 5 oranges and you want something that makes 10 so count them together  5 + 5 = 10

subtraction is when there 10 apples and you eat one and then you count it and 9 so you took one away by eating it  10 - 1 = 9

18) Makala bought 9 plums and we know that they were 7 fewer than Trin.

So that means Trin bought 7 more than Makala.

We can add 9 and 7 to find how many plums Trin bought.

9 + 7 = 16

Trin bought 16 plums.

19) Joey gave 8 peanuts and he has 7 left. To find the total number of peanuts he had can be found by adding 7 and 8.

7 + 8 = 15

There were 15 peanuts in all.

20) We need to find the total number of animals so we will just add all the animals.

6 + 4 + 4 = 14

There are 14 total animals in the park.

21) Clint picked 13 apples and Tim picked 5 less. So subtract 13 and 5 to find the number of apples Tim picked.

13 - 5 = 8

Tim picked 8 apples.

Hope this helps :)

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable