Why do coincide lines have an infinite number of solutions.

Answer: when we graph them, they are one line, coincident, meaning they have all points in common. this means that there are an infinite number of solutions to the system. because this system has at least one solution it is considered to be consistent.

$120

Step-by-step explanation:

Zero pair is a pair of numbers whose sum is zero, e.g. +5, -5. Assigning a negative value to expenditures, Ingrid spent money represents $-120. From the definition, it is deduced that $120 make the zero pair in this case. So, she must earn $120.