Thread: algebra equations

1. algebra equations

After completing 5 of these problems tonight, this one has me stumped!

In a recent year, companies spent a total of $84.8 billion on newspaper, television, and radio ads. The total amount spent on television and radio ads was only$2.6 billion more than the amount spent on newspaper ads alone. The amount spent on newspaper ads was \$5.1 billion more than what was spent on television ads. How much was spent no each form of advertising? (Hint: Let the variables represent numbers of billions of dollars)

Help on this would be greatly appreciated!!!!
Todd

2. Let $n,\ t,\ r$ be the amount of money spent in Newspapers, Tv and Radio, in billions of dollars. Then we have:
$n+t+r=84.8$ (amount spent all together)
$t+r-n=2.6$ (tv and radio 2.6 billions more than newspapers)

We subtract the second equation from the first, and the result is $2n=82.2\Rightarrowx=\frac{82.2}{2}=41.1$.
And we know that $t=n-5.1=41.1-5.1=36$

We substitue the values of $t$ and $n$ in the first equation, and we get $84.4=n+t+r=41.1+36+r\Rightarrow r=84.8-41.1-36=7.7$

So the result is $n=41.1,\ t=36,\ r=7.7$