Which phrase describes a model in science? a structure that is always built to be an exact copy of an object
a structure that is used to represent a complex system
several structures that always represent different things
something that is unique and does not imitate an object

The correct answer is B. A structure that is used to represent a complex system

Explanation:

A scientific model is a structure or set of concepts that aim at representing a natural phenomenon or system. This means a scientific model is not created to be an exact copy of the system but rather to act as a representation, which helps scientists to explain or understand the functions and elements of a system. For example, by creating a model of a specific ecosystem, scientists can better understand the interactions between living organisms in the ecosystem, even though the model is not an exact model of the real ecosystem. According to this, a model in science is "A structure that is used to represent a complex system"

let x be the money she spent so that she can earn the free t-shirt.

since, she already spent $112.49

⇒

also, as per the statement: jennifer must spend $250 or more in order to qualify for a free t-shirt at the store.

then,

we have an inequality i.,e

subtract 112.49 from both sides we get;

therefore, $137. 51 more money does jennifer need to spend so that she can earn the free t-shirt

2 apples

step-by-step explanation:

taking away equals subtraction. 6-4=2