How much did Briana save by purchasing a backpack that cost $45 with a sales promotion of 20% off instead of a backpack that cost $42 with a sales promotion of 10% off?$1.80$3.00$4.80$6.90

Briana saved $1.80

Algebraic expressions in mathematics are a combination of coefficients, numbers, variables, constants and arithmetic operations such as addition, subtraction, multiplication, and division.

Purchasing a backpack that cost $45 with a sales promotion of 20% off

Purchasing a backpack that cost $42 with a sales promotion of 10% off

Briana saved :

they vary. it used to be meat, grain, bread, candy, beverages, donuts, and fruits/vegetables. now they added exercise in.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.