4) which equation can be used to find the value of x? 168 = 18·x + 12·2x 168 = 18·12 + 2x·x 168 = 18·x +…

Explanation:

Step1: Divide the figure into rectangles

The figure can be divided into two rectangles. One rectangle has dimensions (18\mathrm{cm}) and (x\mathrm{cm}), and the other has dimensions (12\mathrm{cm}) and ((x + 2x)=3x\mathrm{cm}).

Step2: Calculate the area of each rectangle

The area of the first - rectangle (A_1=18\times x = 18x) (using the formula (A = l\times w), where (l) is the length and (w) is the width). The area of the second - rectangle (A_2=12\times3x=36x).

Step3: Set up the equation for the total area

The total area of the figure is given as (168\mathrm{cm}^2). So, (A = A_1+A_2), which gives (168 = 18x+12\times3x).

Answer:

(168 = 18\cdot x+12\cdot3x)