Ineed to identify the property that justifies each step to simplify the expression

Are carpet coast $15 per square metre. the total delivery charge is $21 peter buys n squared metres of carpet what is the expression which represents the total cost in $

15 there is a line that includes the point 0,10 and has a slope of 7/4. what is it’s equation in slope intercept form

Agallon of apple juice cost $7 a pack of eight 4.23oz box of apple juice $2.39 which is a better deal