Question

If i have 30 coins consisting of 5 penny and 20 coins. If the total value is £4.05,how many 5 penny coind do i have?

Answer 1

Number of 5 penny coins = 13

Explanation:

Let x & y be the number of your 5 & 20 penny coins respectively, then:
`x+y=30`
`5x+20y=405`
`y=30-x`
`5x+20(30-x)=405`
`5x+600-20x=405`
`-15x=-195`
`x=13`
`y=30-13=17`