Asubstance made of two or more elements that cannot be separated by physical means is called a
a. compound.
b. multi-element.
c. homogeneous mixture.
d. heterogeneous mixture.

Type the correct answer in the box. consider the system of linear equations below. rewrite one of the two equations above in the form ax + by = c, where a, b, and c are constants, so that the sum of the new equation and the unchanged equation from the original system results in an equation in one variable.