Solve {l}{x+y=42}{120x=2*804}

$$\left\{ \begin{array} { l } { x + y = 42 } \\ { 120 x = 2 \times 804 } \end{array} \right.$$

Solve for x, y

$$x = \frac{67}{5} = 13\frac{2}{5} = 13.4$$

$$y = \frac{143}{5} = 28\frac{3}{5} = 28.6$$

Steps Using Substitution

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

$$120x=2\times 804,x+y=42$$

Pick one of the two equations which is more simple to solve for x by isolating x on the left hand side of the equal sign.

$$120x=2\times 804$$

Divide both sides by 120.

$$x=\frac{67}{5}$$

Substitute \frac{67}{5} for x in the other equation, x+y=42.

$$\frac{67}{5}+y=42$$

Subtract \frac{67}{5} from both sides of the equation.

$$y=\frac{143}{5}$$

The system is now solved.

$$x=\frac{67}{5},y=\frac{143}{5}$$