John have some 50cent and 20 cent coins. The value of all the coins is $27. There are twice as many 20 cent coins as 50 cent coins. How many 20 cent coins are there?

There are 60 pieces of 20 cent coins

Step-by-step explanation:

Let the number of 50 cent coins be x.

Let the number of 20 cent coins by y.

Now, we are told that value of all coins is $27.

Also, 50 cent = $ 0.5 and 20 cents = $0. 2

Thus;

0.5x + 0.2y = 27 - - - - - (eq 1)

Now, we are told that there are twice as many 20 cent coins as there are 50 cent coins. So,

y = 2x - - - - (eq 2)

Putting 2x for y in eq 1,we have;

0.5x + 0.2(2x) = 27

0.5x + 0.4x = 27

0.9x = 27

x = 27/0.9

x = 30

Thus, y = 2 * 30 = 60

Thus,there are 60 pieces of 20 cent coins