It is currently 19 Dec 2018, 04:09

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# If 3x + 2y = 24, and 7y / 2x= 7, then y =

Author Message
TAGS:
Moderator
Joined: 18 Apr 2015
Posts: 5205
Followers: 77

Kudos [?]: 1053 [0], given: 4711

If 3x + 2y = 24, and 7y / 2x= 7, then y = [#permalink]  24 May 2017, 02:15
Expert's post
00:00

Question Stats:

87% (02:30) correct 12% (02:04) wrong based on 8 sessions

If 3x + 2y = 24, and $$\frac{7y}{2x}$$$$= 7$$, then y =

[Reveal] Spoiler: OA
$$\frac{48}{7}$$

_________________
GRE Instructor
Joined: 10 Apr 2015
Posts: 1255
Followers: 47

Kudos [?]: 1160 [1] , given: 7

Re: If 3x + 2y = 24, and 7y / 2x= 7, then y = [#permalink]  24 May 2017, 13:09
1
KUDOS
Expert's post
Carcass wrote:

If 3x + 2y = 24, and $$\frac{7y}{2x}= 7$$, then y =

[Reveal] Spoiler: OA
$$\frac{48}{7}$$

Let's deal with 7y/2x = 7 first.
Multiply both sides by 2x to get: 7y = 14x
Divide both sides by 7 to get: y = 2x

ASIDE: At this point, I COULD take 3x + 2y = 24 and replace y with 2x to get 3x + 2(2x) = 24 and solve the equation for x. HOWEVER, the question asks us to find the value of y. So, we'd need to then take that x-value and plug it in to one of the two equations and then solve THAT equation for y.
Rather than solve an extra equation, let's do the following:

We have: y = 2x
Divide both sides by 2 to get: y/2 = x
Now, we can take 3x + 2y = 24 and replace x with y/2 to get 3(y/2) + 2y = 24 [we now have an equation that we can directly solve for y!]
Simplify: 3y/2 + 2y = 24
Multiply both sides by 2 to get: 3y + 4y = 48
Simplify: 7y = 48
Solve: y = 48/7

[Reveal] Spoiler:
48/7

RELATED VIDEO

_________________

Brent Hanneson – Creator of greenlighttestprep.com

Re: If 3x + 2y = 24, and 7y / 2x= 7, then y =   [#permalink] 24 May 2017, 13:09
Display posts from previous: Sort by