Money Problem!

Lisa has $45 more than John. Gina has $25 more than John.

If they have $85 altogether, how much does each creature have?

x = Lisa
y = Gina
z = John

$\begin{array}{lrcll} (1) & x &=& $45+z\\ (2) & y &=& $25+z\\\\ (1)+(2) & x+y &=& $45+z+$25+z \\ & x+y &=& $70+2z \\ \hline \\ (3) & x+y+z &=& $85\\\\ & (x+y)+z &=& $85 \quad & | \quad x+y = $70+2z\\ & $70+2z+z &=& $85 \\ & $70+3z &=& $85 \quad & | \quad -$70\\ & 3z &=& $85 -$70\\ & 3z &=& $15 \quad & | \quad :3 \\ & z &=& \frac{ $15 }{ 3 } \\ & \mathbf{ z } & \mathbf{=} & \mathbf{ $5 }\\ \hline \\ (1) & x &=& $45+z \quad & | \quad z=$5 \\ & x &=& $45+$5 \\ & \mathbf{x} &\mathbf{=}& \mathbf{$50} \\ \hline \\ (2) & y &=& $25+z \quad & | \quad z=$5 \\ & y &=& $25+$5 \\ & \mathbf{y} &\mathbf{=}& \mathbf{$30} \end{array}$

Lisa $50

Gina $30

John $5

Lisa has $45 more than John. Gina has $25 more than John. If they have $85 altogether, how much does each creature have?

Let J be the amount of money that John has, then:

Lisa has=J+45

Gina has=J+25

J+J+45+J+25=85

3J=85-70

3J=15

J=5, Lisa has 45+5=50, Gina has 25+5=30, so that:

5 +50 +30=$85