SOLUTION: I've been having a lot of trouble trying to figure out these two math problems. Any help is greatly appreciated. Its Algebra II. Thank you! The ratio of two numbers is 8 to 5

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Question 853348: I've been having a lot of trouble trying to figure out these two math problems. Any help is greatly appreciated. Its Algebra II. Thank you!

The ratio of two numbers is 8 to 5 Also, three time the larger number is 3 less than 5 times the smaller number. What are the numbers?

A's weight varies inversely as C's weight. When A weighs 20 Kg, C weighs 10 Kg. How much does A weigh when C weighs 5 Kg?

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
1) let x be the larger number and y is the smaller number
x/y = 8/5
3x = 5y - 3
take first equation and cross multiply
5x = 8y
now solve for x
x = 8y/5
substitute for x in second equation
3(8y/5) = 5y - 3
multiply both sides of = by 5
24y = 25y - 15
y = 15
substitute for y in first equation
x/15 = 8/5
5x = 8 * 15
5x = 120
x = 24
the larger number is 24 and the smaller number is 15
2) A = k / C
if A = 20 kg, then C = 10 kg
20 = k / 10
k = 200
now if C = 5 kg, then
A = 200 / 5
A = 40 kg