Math question

[MowgliR]

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If A and B's income are in a 3:2 ratio, their expenses are in a 5:3 ration, and A saves $100 while B's expense is $30, what is A's income?


How should approach a problem like this?

 

[RSD2014]

If A and B's income are in a 3:2 ratio, their expenses are in a 5:3 ration, and A saves $100 while B's expense is $30, what is A's income?


How should approach a problem like this?

Do you have an answer? Is A's income $150?

Expense ratio: 5x : 3x
B's expense is $30 = 3x so x= $10
A's expense is 5x = 5($10) = $50

A's expense : B's expense = 5:3
$50:$30 = 5:3


A's Income - expense = saving of $100
3y - $50 = $100
3y = $150 = A's income
y = 50

B's income = 2y = 2(50) = 100

A's income : B's income = 3:2
150:100 = income ratio 3:2

 

[mashinka]

So I would say that for A: 3x - 5y = 100
B: 2x - 3y = -30
now just solve from there by multiplying equation A by 2 and equation B by -3 to get:

6x - 10y = 200
-6x + 9y = 90
y= -290
x= 420

So if income of A.is 3x, then 3(420) = 1260.
Is that right?

 

[ZFT]

Do you have an answer? Is A's income $150?

Expense ratio: 5x : 3x
B's expense is $30 = 3x so x= $10
A's expense is 5x = 5($10) = $50

A's expense : B's expense = 5:3
$50:$30 = 5:3


A's Income - expense = saving of $100
3y - $50 = $100
3y = $150 = A's income
y = 50

I agree with $150. Here's how I set it up

Expense: A/B = 5/3 = 50/30

100 + 50 = $150

As it turns out, A/B = 3/2 (income) is useless info for this question, I stared at it for 10 seconds before realizing this. Hopefully the testmakers won't try too many of these on the real thing.