Tom observes 240 birds. He notices that 12 of them have blue tail feathers. The next day he spots 40 birds with blue tail feathers. How many birds did he view in total that day?

800

Step-by-step explanation:

240/12= 20 x 40 = 800

21

step-by-step explanation:

11279

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