A brush cost $2 more than a comb. The brush and comb together cost $3.78. Find the cost of each. I'm trying to use the equation 2x+x=3.78 but I don't think this is right. Help?

Question

A brush cost $2 more than a comb. The brush and comb together cost $3.78.  Find the cost of each.                                                                       I'm trying to use the equation 2x+x=3.78 but I don't think this is right. Help?

zepdrix · Answer

so a brush cost 2 more than a comb ---> comb + 2 = brush
brush and comb cost 3.78 -----------> brush + comb = 3.78

you have a system of equations, add them.. subtract them.. do something to where one of your variables cancel out and solve for the other =)
then with the value you get, plug the value into one of your original equations to find the other! yayyyy math!

anonymous · Answer

@Carly33 what class is this?  Have you done systems of 2 equations with 2 unknowns yet?

anonymous · Answer

Pre-Algebra.

anonymous · Answer

Ok... you often get these in pre-algebra classes where you haven't had the stuff zepdrix showed (it was right, just stuff you haven't seen yet)

anonymous · Answer

A good equation to use is "comb" + "2 dollars more than comb" = 3.78.  Do you see why?

anonymous · Answer

so if comb is  "x", you would have x + (2 + x) = 3.78
                                                      2x + 2 = 3.78
                                                       2x = 1.78
                                                         x = (1.78 / 2) = 0.89

anonymous · Answer

Ok, I think I just got it. x= brush & y=comb so 2 + 2y = 3.78 so y= .89??? and then I plug that back in, right?

anonymous · Answer

That's the comb price, 0.89.  And the brush price is 2 dollars more, or 2.89.

Check your work after, also... a very good habit:  0.89 + 2.89 = 3.78

And now you can say "yay math"  :)

anonymous · Answer

Yay math, lol. thank you!!

anonymous · Answer

My point was that in pre-algebra, they don't teach you to use two different variables like x and y... they just take the short cut and want you to say "one variable" and "some number plus that variable".

But the BEST way is to use the x and y... it's just assumed that doing that in this class at this point might be too much for you.   :)  You will get there soon enough though!  :)

anonymous · Answer

Ok, thank you very much. Word problems just intimidate me.

anonymous · Answer

Be BRAVE :)

anonymous · Answer

And just take it slow... talk it out as you write the math expression to go with the word problem... it gets easier with practice.

anonymous · Answer

:) thanks again!

anonymous · Answer

you are most welcome :)  Good luck!