Solve {l}{M+F=80+70}{S=M-15}{S=60}{m=M}

$$\left. \begin{array} { l } { M + F = 80 + 70 } \\ { S = M - 15 } \\ { S = 60 } \\ { m = M } \end{array} \right.$$

Solve for M, F, S, m

$$M=75$$

$$F=75$$

$$S=60$$

$$m=75$$

Solution Steps

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

$$60=M-15$$

Swap sides so that all variable terms are on the left hand side.

$$M-15=60$$

Add 15 to both sides.

$$M=60+15$$

Add 60 and 15 to get 75.

$$M=75$$

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

$$m=75$$

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

$$75+F=80+70$$

Add 80 and 70 to get 150.

$$75+F=150$$

Subtract 75 from both sides.

$$F=150-75$$

Subtract 75 from 150 to get 75.

$$F=75$$

The system is now solved.

$$M=75 F=75 S=60 m=75$$