Solve {l}{y+6=21}{x+7=5}{z=y+x}{text{Solvefor}atext{where}}{a=z}

$$\left. \begin{array} { l } { y + 6 = 21 }\\ { x + 7 = 5 }\\ { z = y + x }\\ { \text{Solve for } a \text{ where} } \\ { a = z } \end{array} \right.$$

Solve for y, x, z, a

$$a=13$$

Solution Steps

Consider the first equation. Subtract 6 from both sides.

$$y=21-6$$

Subtract 6 from 21 to get 15.

$$y=15$$

Consider the second equation. Subtract 7 from both sides.

$$x=5-7$$

Subtract 7 from 5 to get -2.

$$x=-2$$

Consider the third equation. Insert the known values of variables into the equation.

$$z=15-2$$

Subtract 2 from 15 to get 13.

$$z=13$$

Consider the fourth equation. Insert the known values of variables into the equation.

$$a=13$$

The system is now solved.

$$y=15 x=-2 z=13 a=13$$