20 mm
16 mm
Area of base
is 440.4 mm

x = 6

Explanation: This problem can be done either of two ways by putting the variables together on the left and the numbers together on the right or vice versa.

If we put our variables together on the left and our numbers together on the right, we would start by subtracting

2x from both sides to get 3x + 4 = 22.

Next, we subtract 4 from both sides to get 3x = 18.

Finally, we divide both sides by 3 to get x = 6.

Note that we can check our answer by plugging 6 back in

for both of the x's in the original equation.

So go ahead and check the answer and see if it works.