Climatologists are monitoring the sea surface tempera- ture off the coast of Nigeria. When they average the
monthly temperatures in an attempt to predict the onset
of diseases such as cholera, malaria, and dengue fever,
they can add the daily temperatures in any order. What
mathematical property does this demonstrate?

x is variable or an unknown value to find

example:

2x = 5 which means x = 3

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

answer: y=4000x+14000

step-by-step explanation: