When is estimation an effective way to determine an answer

An estimation is an effective way to determine an answer if

- the exact answer is not very important (for example it's enough to know you need 1000 grams of flower, you don't need tknow if it's 1001 or 1003)

-it's more important that the answer is fast than accurate - for example if you need to assess if 5 cups with 83 grams each will fit into a 350 grams container  - the answer is "around 400" grams, and it's enough to tell you it's not enough

y=-1/4x-1

Step-by-step explanation:

The Y intercept is at -1 so the end of the equation should be -1 and not -4.

The graph is decreasing by 1 block down every 4 blocks to the right so the equation needs -1/4x as the slope.

Sorry I'm bad at explaining this.