With 6, & 7 i'm so lost and i don't know if 6 is 100% right

Me, prove a quadrilateral with vertices g(1,-1), h(5,1), i(4,3) and j(0,1) is a rectangle using the parallelogram method and a rectangle method.

Neal buys a board game. he pays for the board game and pays $1.54 in sales tax. the sales tax rate is 5.5%. what is the original price of the board game, before tax

Agrasshopper weighs 0.89 grams. express the grasshopper’s weight in scientific notation.