x = no. of 10 peso coins
10x = total value of the no. of 10 peso coins
2x = no. of 5 peso coins
5 (2x) or 10x = total value of 5 peso coins
10x + 10x = 80
20x = 80
20x(1/20) = 80 (1/20)
20/20x = 80/20
1x = 80/20
x = 4
x = 4 = no. of 10 peso coins
2x = 2 x 4 = 8 = no. of 5 peso coins
Therefore, the answer is:
There are 4 ten peso coins and 8 five peso coins.