4. Elena noticed that, nine years ago, her cousin Katie was twice as old as Elena was then,

Then Elena said, "In four years, I'll be as old as Katie is now!" If Elena is currently e years

old and Katie is k years old, which system of equations matches the story?

k - 2e + 9 = 0

k - e - 4 = 0

Step-by-step explanation:

Given that Elena is currently e years  old and Katie is k years old. Now, nine years ago, Katie was twice as old as Elena was.

So, k - 9 = 2(e - 9)

⇒ k - 2e + 9 = 0 (1)

And, in four years, Elena will be as old as Katie is now.

So, k = e + 4

⇒ k - e - 4 = 0 (2)

Therefore, the equations (1) and (2) matches the conditions. (Answer)

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

the answer on ed. is:

c. "the graph of f(x) has exactly two x-intercepts."

hope i could someone! : )