Question

a) if $f(x) = 15 - 2x$, find $x$ if $f(x) = 13$.
b) if $f(x) = 15 - 24x$, find $x$ if $f(x) = 159$.

Explanation:

Part (a)

Step1: Substitute \( f(x) \) with 13

We know \( f(x) = 15 - 2x \) and \( f(x) = 13 \), so substitute to get \( 13 = 15 - 2x \).

Step2: Solve for \( x \)

Subtract 15 from both sides: \( 13 - 15 = -2x \), which simplifies to \( -2 = -2x \).
Divide both sides by -2: \( x = \frac{-2}{-2} = 1 \).

Step1: Substitute \( f(x) \) with 159

Given \( f(x) = 15 - 24x \) and \( f(x) = 159 \), substitute to obtain \( 159 = 15 - 24x \).

Step2: Solve for \( x \)

Subtract 15 from both sides: \( 159 - 15 = -24x \), so \( 144 = -24x \).
Divide both sides by -24: \( x = \frac{144}{-24} = -6 \).

Answer:

\( x = 1 \)

Part (b)