Question

I can tell the difference between an equation and an expression and solve for the variable.

Cedric read the following story problem and wrote a correct equation to represent the
situation. Myron got his paycheck of $20 this week. He had $10 left after he spent m
dollars on a new video game. How much did the video game cost?
6.
Cedric's correct equation: 20 m = 10
a. How did Cedric know that this was an equation and not an expression?
b. Why subtract m from 20 rather than add m to 20?

Answer 1

a. Cedric used an equal sign (=) in the equation, indicating equality between two expressions, making it an equation. This means that the amount of money Myron had before spending on the video game is equal to the amount he had left after spending. So, it's an equation representing a balance or equality between the two quantities.

b. Cedric subtracted m from 20 because Myron spent money, causing his balance to decrease. Adding m to 20 would imply an increase in his balance, which goes against the problem's context.