Find the area of the rectangle below.
(3x + 4) feet
(x + 3) feet

3x² + 13x + 12 ft²

Step-by-step explanation:

To work out the area of a rectangle you have to multiply the length and width together. In this case the length is 3x + 4 and the width is x + 3

So

( 3x + 4 ) × ( x + 3 )

Remember FOIL when expanding brackets

F = First two so 3x × x = 3x²

O = Outer two so 3x × 3 = 9x

I = Inner two so 4 × x = 4x

L = Last two so 4 × 3 = 12

but we aren't finished

3x² + 9x + 4x + 12 = 3x² + 13x + 12

Don't forget unit! ft²

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.