Answer:
a : b = 25 : 9
Step-by-step explanation:
(3a - 5b) : (3a + 5b) = 1 : 4
Product of extremes = product of means
(3a - 5b) *4 = (3a +5b) * 1 {Distributive property}
3a * 4 - 5b*4 = 3a + 5b
12a - 20b = 3a + 5b
Add 20b to both sides
12a = 3a + 5b + 20b
12a = 3a + 25b
Subtract 3a from both sides
12a - 3a = 25b
9a = 25b
a:b = 25 : 9
Kala call lasted for 0.36 minutes
<em><u>Solution:</u></em>
Given that Kala purchased a prepaid phone card for $15
Long distance calls cost $12 a minute using this card.
If the remaining credit on her card is $10.68
To find: Number of minutes her call lasted
Let "x" be the number of minutes her call lasted
Cost of 1 minute = $ 12
Total balance = $15
Remaining balance = $ 10.68
So we can frame a equation as:
Total balance = Remaining balance + Cost of 1 minute x number of minutes her call lasted
So her call lasted for 0.36 minutes