Solve (42+20):4-2*(9:3)-2*[18+3*(13-9)-5]=

$$( 42 + 20 ) : 4 - 2 \cdot ( 9 : 3 ) - 2 \cdot [ 18 + 3 \cdot ( 13 - 9 ) - 5 ] =$$

Evaluate

$$-\frac{81}{2}=-40.5$$

Solution Steps

Add 42 and 20 to get 62.

$$\frac{62}{4}-2\times \frac{9}{3}-2\left(18+3\left(13-9\right)-5\right)$$

Reduce the fraction \frac{62}{4} to lowest terms by extracting and canceling out 2.

$$\frac{31}{2}-2\times \frac{9}{3}-2\left(18+3\left(13-9\right)-5\right)$$

Divide 9 by 3 to get 3.

$$\frac{31}{2}-2\times 3-2\left(18+3\left(13-9\right)-5\right)$$

Multiply 2 and 3 to get 6.

$$\frac{31}{2}-6-2\left(18+3\left(13-9\right)-5\right)$$

Convert 6 to fraction \frac{12}{2}.

$$\frac{31}{2}-\frac{12}{2}-2\left(18+3\left(13-9\right)-5\right)$$

Since \frac{31}{2} and \frac{12}{2} have the same denominator, subtract them by subtracting their numerators.

$$\frac{31-12}{2}-2\left(18+3\left(13-9\right)-5\right)$$

Subtract 12 from 31 to get 19.

$$\frac{19}{2}-2\left(18+3\left(13-9\right)-5\right)$$

Subtract 9 from 13 to get 4.

$$\frac{19}{2}-2\left(18+3\times 4-5\right)$$

Multiply 3 and 4 to get 12.

$$\frac{19}{2}-2\left(18+12-5\right)$$

Add 18 and 12 to get 30.

$$\frac{19}{2}-2\left(30-5\right)$$

Subtract 5 from 30 to get 25.

$$\frac{19}{2}-2\times 25$$

Multiply 2 and 25 to get 50.

$$\frac{19}{2}-50$$

Convert 50 to fraction \frac{100}{2}.

$$\frac{19}{2}-\frac{100}{2}$$

Since \frac{19}{2} and \frac{100}{2} have the same denominator, subtract them by subtracting their numerators.

$$\frac{19-100}{2}$$

Subtract 100 from 19 to get -81.

$$-\frac{81}{2}$$

Factor

$$-\frac{81}{2} = -40\frac{1}{2} = -40.5$$