Hello! So the sweater was marked off by 20% and the sale price is $60. To find the original price of the sweater, we can write and solve a proportion. Set it up like this:
60/x = 80/100
This is because 60 is a part of the whole (the original price), and even though the price was marked down by 20%, you still pay 80% of that price. Let's cross multiply the values. 60 * 100 is 6,000. 80 * x is 80x. That makes 6,000 = 80x. Now, divide each side by 80 to isolate the x. 80x/80 cancels out. 6,000/80 is 75. Let's check this. 75 * 80% (0.8) is 60. There. x = 75. The regular price of the sweater is $75.
1 is neither prime nor a composite number because it only has 1 divisor, 1 and 1, and it doesn't have more than 2 integral divisors, like stated, it only has 1. So it falls in neither category.
