2x-y=23 & x-9=-1 by substitution

x=8, y=-7. (8, -7).

Step-by-step explanation:

2x-y=23

x-9=-1

x=-1+9=8

x=8

2(8)-y=23

16-y=23

y=16-23=-7

x=8, y=-7. (8, -7).

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40