Writing linear equations

This equation will represent situations where something is being added to or subtracted from the x-value. 

Look out for words in word problems like: more than, less than

This equation will represent situations where the x-value is being multiplied or divided. 

Look out for words in word problems like: each, per

We will write the equation in the form of y = mx or y = x + b for the situation.

Samantha had to pay $4 more than Joe had to pay for a video game.

I spy the key words: "more than"

It seems to be an addition

My answer is:  $y=x+4$  

We will write the equation in the form of y = mx or y = x + b for the situation.

Oranges at the super market cost $0.89 each.

I spy the key words: "each"

It seems to be a multiplication

My answer is:  $y=0.89x$