Can coins be attracted by magnets?

Can coins be attracted by magnets?

1. Coins that can be attracted by magnets
one yuan
Pentagonal
A one horned one
2. Coins that cannot be attracted by magnets
Aluminum dime, nickel, dime, dime
Various coins before liberation

There are 10 dimes, 50 cents and 10 yuan coins each. 15 pieces are taken out from them, and the total value is 7 yuan. How many dimes, 50 cents and 1 yuan coins should be taken? Using the solution of the system of three variable first order equations, fast

Let the unknown variables be ingeniously set as X, y, 15-x-y
If it is a corner of X pieces, five corners of Y pieces, one yuan (15-x-y) pieces, then the one yuan multiplied by 10 will make the equation more complex,
Unit angle
Then the equation is obtained
10x+5y+(15-x-y)=70
conversion
9x+4y=55
Because x, y and (15-x-y) are greater than or equal to 0 and less than or equal to 10
So X

At present, there are 10 dimes and 10 dimes each. How many coins worth 7 yuan and 15 Jiao 1 yuan are taken out from them?

Let X be a dime and y be a dime, then x and y are integers, and 0 ≤ x, y ≤ 10, 0 ≤ x + y ≤ 15. From the problem, the equation x + 5Y + 10 × (15-x-y) = 70 is simplified, and y = 16 - (9 / 5) × x is obtained because X and y are integers, and 0 ≤ x, y ≤ 10, 0 ≤ x + y

At present, there are ten dimes and ten dimes each, and 15 coins are taken out from them, totaling 7 yuan. How many coins are there for each of 1 jiao, 5 jiao and 1 yuan

Let X of 1, y of 5 and Z of 1
x+5y+10z=70
x+y+z=15
obtain
x=5(z+1)/4 (0

What percentage of the original price is a product sold at a price reduction of 30%? What's the original price of a product when it's sold at a 20% discount? How much is the original price of this product? In these two questions, is it the same to sell a commodity at a price of 30% and a commodity at a 20% discount?

If the original is set as X, the current price is 0.7x, and the current price is equal to 70% of the original
84/(1-o.8)=420

A product is sold at a 20% discount, 84 yuan cheaper. How much is the original price?

84÷（1-80%），
=420 yuan;
A: the original price is 420 yuan

How much is the original price of 40 yuan for a 20% discount?

40 × (1-0.8) = 200 yuan

A 20% discount on a commodity is 80 yuan cheaper. How much is the original price of this product?

If the original price is x, then x-0.8x = 80, x = 400

A product is sold at a 20% discount, 84 yuan cheaper. How much is the original price?

84÷（1-80%），
=420 yuan;
A: the original price is 420 yuan

1. A piece of clothing is sold at 80% discount, which is 80 yuan cheaper. How much is the original price? 2. How much is the original price when the price of a garment is reduced by 20%, 80 yuan? 3. The price of a dress is 80% lower, 80 yuan cheaper. How much is the original price?

(1) 80 / 80% = 100 yuan
(2) 80 / (1-80%) = 400 yuan
(3) See (2)