Using the equation, substitute Amelia’s age (12 on her birthday) for x in the equation.

y = 0.5x + 80
y = 0.5(12) + 80
y = 6 + 80
y = 86

So 86% of the 12-years-olds in this scenario are satisfied with their tablet.

In the second line of equations, How does 0.5(12) make the 6 in the third line?

  the multiplication is done

Step-by-step explanation:

In math, the multiplication symbol is often "implied" by writing factors next to each other. The term 0.5x means 0.5 is multiplied by x. When we substitute 12 for x in that term, its meaning does not change. It still means 0.5 is multiplied by 12.

Any expression anywhere can be put in parentheses. So, the expression 0.5(12) is another way to write 0.5×12.

 0.5(12) becomes 6 by carrying out the multiplication. Half of 12 is 6.

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!