Ie 32^2 - 4ac=0 so ac=256 and a+c=130
So, that means:2 equations ac=256 a+c=130 ie c=130-a
So,a(130-a)=256 so 130a -a^2=256 ie a^2-130a +256=0 (a-2)(a-128)=0
Finally,giving a= 2 or a=128 so, a=2 c=128 or a=128 c=2
Since, a>c , a=128 and c=2 ie (128,2)
Answer:
Carrie and Joan have 80 nickels and 40 dimes, respectively, and each one has an amount of money of 4 US dollars.
Step-by-step explanation:
Let be 
and 
the amounts of nickels and dimes that Carrie and Joan have, as 
the total amount of money that both Carrie and Joan have. A nickel is a five cent coin and a dime is a ten cent coin.
The following equations are constructed after a careful reading on statement:
Carrie's amount of money:
(Eq. 1)
Joan's amount of money:
(Eq. 2)
Relation between amounts of coins:
(Eq. 3)
First we eliminate by equalizing (Eq. 1) and (Eq. 2):
Then, we reduce the resulting formula by (Eq. 3):
And rest of variable are now determined:
Carrie and Joan have 80 nickels and 40 dimes, respectively, and each one has an amount of money of 4 US dollars.
The relation between a and s is given to be:
a = 640s
where,
a = number of acres
s = number of square miles
We are to find the number of acres for 7.5 square miles.
This means, s = 7.5
Using the value in the formula, we get:
a = 640 x 7.5 = 4800 acres
So the answer to this question is option B
I would say 80, because without an estimate it'd be 79 and 79x5=395. So 80x5=400, which is the estimate of 395. So 80 is the answer
