I need help quick please help me thnak you

28 numbers

Step-by-step explanation:

There is a distance of 81 between -0.5 and 80.5. Divide this number by 3, since you are only counting every third number and you will get 27, but you need to count the first number, which has been excluded. Add one more to get the answer, 28.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18