Elsa received a $90 gift card for a coffee store. She used it in buying some coffee that cost $7.54 per pound. After buying the coffee, she had $44.76 left on her card. How many pounds of coffee did she buy?

she bought lots of coffee

Step-by-step explanation:

answers

\3. yes the presentation (i.e. odd numbers being written as differences of two squares) is possible for all odd natural number however the presentation may not be unique. for example,  57=112−82=292−28257=112−82=292−282.

\4. 2 can't be written as a difference of two squares because 4-1=3 and 1-1=0 and the difference of squares grows to integers larger that 3.

can i get some in proving questions 1 and 2?