How does estimating an addition or subtraction problem help you know if an answer is reasonable?

It helps you know if the answer is reasonable because when you do the work and get your answer, you can check if it is close to your estimate, and if it is, it is most likely correct. On the other hand if it is not close to the estimate it is most likely wrong, unless you estimated incorrectly.

Step-by-step explanation:

the simplified form is

step-by-step explanation:

we want to simplify the expression,

let us change the middle bar to a normal division sign to obtain,

we multiply the first fraction by the reciprocal of the second fraction to obtain,

we factor to obtain,

we cancel the common factors to get,

we simplify to get,

the correct answer is b

use distributive property on all like terms and change your signs if you have a double negative or if you have positive/negative