How do you know that a =6 is a solution to a+5=11?

a + 5 = 11

You need to isolate the variable by subtracting from both sides

a + 5 - 5 = 11 - 5a = 6

The Addition/Subtraction Property of Equality states that if you add or subtract the same number to both sides of an equation the two sides still remain equal

:))

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!

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72