Give me explain associative property of addition? ?

Ascale drawing of a lake has a scale of 1 cm to 80 m. if the actual width of the lake is 1000 m what is the width of the lake on the scale drawing

Adepartment store purchases screen-printed t-shirts at a cost of $5 per shirt. they mark up the price 150% (making the selling price 250% of the store's purchase price) and put them on the sales floor. every month that a t-shirt doesn't sell, the store reduces the selling price by 25%.

Find x to the nearest hundredth place