Please help i'm only in 5th grade

Amira is painting a rectangular banner 2 1/4 yards wide. the banner will have a blue background. amira has enough paint to cover 1 1/2 square yards of the wall. the school colors are blue and yellow, so amira wants to add yellow rectangles on the left and right sides of the blue rectangle. the yellow rectangles will each be 3/4 yards wide and the same height as the blue rectangle. what will be the total area of the two yellow rectangles?

Solve these problems: 1.what is the perimeter of an equilateral triangle with sides measuring 6cm? 2. a regular pentagon has sides measuring 3.2 cm. what is its perimeter? 3. a regular decagon has sides of 3.5mm . what is it’s perimeter? 4. a regular octagon has a perimeter of 64cm. what is the length of one of the sides? 5. a regular hexagon has a perimeter of 72mm . what is the length of one of the sides? 6. what is the perimeter of a rhombus with sides measuring 11m?

How do i i solve this equation? -18 = x/3 + 3