Brad wants to buy flowers for his friend with $15. The daisies are $1 each and the roses are $3 each. He buys 3 more daisies than roses how much did the roses cost?

D + 3r = 15

d = r + 3

r + 3 + 3r = 15

4r + 3 = 15

4r = 15 - 3

4r = 12

r = 12/4

r = 3 ... he bought 3 roses, at $ 3 per rose = $ 9 <==

d = r + 3

d = 3 + 3

d = 6 ... he bought 6 daisies, at $ 1 per daisy = $ 6

Brad wants to buy flowers for his friend with $15. The daisies are $1 each and the roses are $3 each. He buys 3 more daisies than roses how much did the roses cost?

-daisies=x - - roses=y-

x+y=15

the sentence how he buys 3 more daisies than roses so ...

(y=x-3)

you then plug in the value of y in the equation to have only one variable ...

x + 3 (x-3) = 15

you then multiply 3 to the parenthesis ...

x+3x-9=15

then add 9 on both sides ...

4x=24

and then divide 4 on both sides ...

x=6

if you plug the value of x (daisies) in the equation ...

6+y=15

you subtract 6 on both sides and get ...

y=9

you can also get the answer by solving for y with x ...

y=3 (x-3)

(x=6)

plug in x ...

y=3 (6-3)

y=3 (3)

y=9

Answer: the roses cost $9