150% of what number is 24?

What is the slope of the line shown below?

Jamie went to home depot.she bought 25 bags of soil that cost $9 per bag.she bought 15 pots at $8 each, and she bought 23 bags of pebbles at $15 each.she used a coupon that gave her $5 off for every 100 dollars she spent. how much did jamie pay at the end?

Complete the equation of the line through (−10,3) and (−8,−8). use exact numbers.