Why can the formula below be used to find the area of a square?
1/2 (d1d2)

Danielle earns a 7.25% commission on everything she sells at the electronics store where she works. she also earns a base salary of $750 per week. what were her sales last week if her total earnings for the week were $1,076.25?

3x + 4y = 5 x- 3y = -7 solve by substitution

I'm a polygon i have no parallel lines i am formed 3 line segments i have one right angle two of my angles are angles what am i