Please help me with this homework show me how you get it and the answer

The value of x in this system of equations is 1. 3x + y = 9 y = –4x + 10 substitute the value of y in the first equation: combine like terms: apply the subtraction property of equality: apply the division property of equality: 3x + (–4x + 10) = 9 –x + 10 = 9 –x = –1 x = 1 what is the value of y?

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.

Over the course of a month, a person's weight decreases. what type of relationship is this? a. positive relationship