Which of the following equations represents the line with a slope of 5/2 and a y-intercept of 1?

y = 5/2x + 1

y = 2/5x - 1

y = 2/5x + 1

y = 5/2x - 1

The price of a box of 15 cloud markers is $12.70. the price of a box of 42 cloud markers is $31.60. all prices are without tax, and the price of the packaging is the same for any size. how much would 50 cloud markers in a box cost? write an equation which will tell the price p for the number n markers in the box.