3. Where do the lines y = 3x + 5 and 5x + 5y = 25 intersect?

Question

anonymous · Answer

(A) (7, 6)

 (B) (5, 0) 

(C) (0, 5) 

(D) (4, 2)

anonymous · Answer

The answer is C but I don't know how

nnesha · Answer

there are different ways to find solution 
graphing 
substitution 
elimination 
matrices

nnesha · Answer

graphing is easy 
just type equation into the calculator  
to check your answer plugin x =0 and y=5  in both equations

anonymous · Answer

I can't use calculators for the test

nnesha · Answer

alright thats fine 
then substitution method

anonymous · Answer

i keep getting 20x what do I do 
next

nnesha · Answer

or elimination 
for this equation  (first equation) is already solved for y so substitution would be easy

nnesha · Answer

Nnesha:  substitution:  replace y with first equation 

Nnesha:  5x+5(3x+5)=25

nnesha · Answer

what about 25 ??

anonymous · Answer

I don't know what to do next

anonymous · Answer

i substituted it but i got a different answer

nnesha · Answer

5(3x+5)
distribute by 5
15x+25 $$\huge\rm \color{Red}{5x+15x}+25=25$$
combine like terms that's how u got 20x
$$\color{Red}{20x }+25=25$$

nnesha · Answer

can you solve for x??^^

anonymous · Answer

0?

nnesha · Answer

right 
subtract 25 both sides |dw:1447006150028:dw|
0 divide by anything = 0 so yes that's correct