(picture included) where did i go wrong here? (using the combination method)

I guess by "combination" you mean elimination. You multiplied the second equation by -2, so the system is

Then eliminating by adding the first equation to the second, you'd end up with

so you all you did was forget about the -1 from the first equation.

From here, you have

so if , then . So the solution would be (2, -1).

ipuy6tygy

step-by-step explanation:

d. bc = 12 and ef = 16

step-by-step explanation:

we are given that δabc : δdef such that .

also, it is given that

so, from the options, we need that .

a.

b.

c.  

d.

as, we can see that only option d gives the same ratio as i.e. .

hence, the possible lengths are bc = 12 and ef = 16.