Chapter 1.8, Problem 1STP

For Exercises $1-5,$ choose the correct letter.

Which equation is true?

A. $25-(-18)=7$

B. $\frac{1}{3}(-9)-6=-9$

C. $25(-2)+7=-39+4$

D. $-19+8(-2)=-7(-5)$

To determine

To find: The equation which is true.

Answer to Problem 1STP

The equation which is true is $\frac{1}{3}(-9)-6=-9$ which is option B.

Explanation of Solution

Given information: Four options given to find true equation, $A.25-(-8)=7$ , $B.\frac{1}{3}(-9)-6=-9$ , $C.25(-2)+7=-39+4$ , $D.-19+8(-2)=-7(-5)$ .

Calculation:

By solving the equation in option A,

$\begin{array}{l}25-(-18)=7\\ \Rightarrow 25+18=7\\ \Rightarrow 43=7\end{array}$

This equation is not true.

By solving the equation in option B,

$\begin{array}{l}\frac{1}{3}(-9)-6=-9\\ \Rightarrow -3-6=-9\\ \Rightarrow -9=-9\end{array}$

This equation is true.

By solving the equation in option C,

$\begin{array}{l}25(-2)+7=-39+4\\ \Rightarrow -50+7=-35\\ \Rightarrow -43=-35\end{array}$

This equation is not true.

By solving the equation in option D,

  $\begin{array}{l}-19+8(-2)=-7(-5)\\ \Rightarrow -19-16=35\\ \Rightarrow -35=35\end{array}$

This equation is not true.

  $\therefore$ The equation in option B is true.