A, B and D are already rational numbers, 0.4 itself is a rational number, two rational numbers make a product of rational number.
So A, B, D are the correct choices.
Are you sure it asks for rational numbers, not irrational number?
a function that model the number of people that receives email in week t is 
.
<u>Step-by-step explanation:</u>
Here we have , Tobias sent a chain letter to his friends . The number of people who receives the email increases by a factor of 4 in every 9.1 weeks , and can be modeled by a function P, which depends on the amount of time t weeks . Tobias initially sent letter to 37 friends . We need to write a function that model the number of people that receives email in week t . Let's find out:
Basically it's an exponential function as
, In question initial value is 37 & and for every 9.1 weeks there is increase in people by a factor of 4 i.e.
⇒ 
But , wait ! People increase in every 9.1 weeks not every week so modified equation will be :
⇒
Therefore , a function that model the number of people that receives email in week t is .
The explanation of using Literal equations to solve for a given variable is as explained below.
How to solve Literal Equations?
Literal equations are equations containing two or more variables; at least one independent variable and one dependent variable
To solve a literal equation means to rewrite the equation so a different variable stands alone on one side of the equals sign. We have to be told for which variable we want to solve.
Linear equations in one variable may take the form ax + b = 0 and are solved using basic algebraic operations.
We begin by classifying linear equations in one variable as one of three types: identity, conditional, or inconsistent. An identity equation is true for all values of the variable.
Read more about Literal Equations at; brainly.com/question/1852246
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I think the answer to this is 4 I think
