LCM of 1505 and 1600​

Find an equation of variation where y varies directly as x and y 75 when x5, findy when x is 1

Arectangular lawn is 14m long and 10m wide. a strip of uniform width is mowed around the outside of the lawn. how wide is the strip when the area of the unmowed portion of the lawn is 12m². (the answer is 4m, but i need to know how to solve it)

Robbie goes to the supermarket to buy a bag of chips he brings $20 to the store and pays 3.$79 for the chips . on the way home he finds 1.35 dollars in coins on the sidewalk how much money does robbie have when he gets home