Solve {l}{90=4*5x+1200/x}{y=4}{text{Solvefor}ztext{where}}{z=y}

$$\left. \begin{array} { l } { 90 = \frac{4 \cdot 5 x + 1200}{x} }\\ { y = 4 }\\ { \text{Solve for } z \text{ where} } \\ { z = y } \end{array} \right.$$

Solve for x, y, z

$$z=4$$

Solution Steps

Consider the first equation. Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.

$$90x=4\times 5x+1200$$

Multiply 4 and 5 to get 20.

$$90x=20x+1200$$

Subtract 20x from both sides.

$$90x-20x=1200$$

Combine 90x and -20x to get 70x.

$$70x=1200$$

Divide both sides by 70.

$$x=\frac{1200}{70}$$

Reduce the fraction \frac{1200}{70} to lowest terms by extracting and canceling out 10.

$$x=\frac{120}{7}$$

The system is now solved.

$$x=\frac{120}{7} y=4 z=4$$