Símbolo que representa la diferencial de la variable independiente

hope this .

r3t40

b. f(x) = –√x + 3this is the correct answer

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x

i think this is a open ended question but i agree with other guy who said you should ask it at english section