Question 1150851

Charles is four times as old as his daughter Nina.Eight years ago he was ten times as old as Nina. How old is Charles today?
<pre>My 1st "let" statement is usually associated with the variable that's being sought. In other words, here I would say, "Let Charles' age be C."
But, this would involve FRACTIONS, and that's a topic that most would rather stay away from, you included, I'd assume! So, I'll go with Nina.

Let Nina's age be N
Then Charles' is 4N
We then get: 4N - 8 = 10(N - 8)
4N - 8 = 10N - 80 
4N - 40N = - 80 + 8
- 6N = - 72
N, or Nina's age is: {{{matrix(1,3, (- 72)/(- 6), "=", 12)}}}
Therefore, Charles is: {{{highlight_green(matrix(1,4, 4(12), "=", 48, years-old))}}}