i need help on algebra

Question

If y varies directly with x and x = 110 and y = 66, find y when x = 80.

Answer 1

Hi!

This is a direct variation problem, which uses the formula y=kx.

Substitute your values for x and y into the equation, and you'll get 66=k110.

Next, solve for the value of k by using inverse operations. k=66/110 which simplifies to k=3/5 or 0.6

Now you have your equation for the direct variation y=0.6x.

Substitute your new value in for x and you'll have y=0.6(80)

Therefore, y=48 when x=80.

Answer 2

Hi,

when x = 110 you know y = 66

Now, you need to find y, when x has changed to 80

for these kind of questions you need to make equation such as:

previous X / previous y = present x / present y

110/66 = 80/y I am sure you know how solve this equation ( cross multiplication)

110 y = 66 * 80 both sides divided by 110

y = (66 * 80 ) / 110

y = 48

I hope it is useful, please let me know if you have any question.

Minoo

Answer 3

This is a similar problem Camila.

Y varies directly with x gives you this type of relationship: y/x = k or (y = kx) either way

Now, just start plugging in given information to solve for k, and then use it on the second part of the problem to solve for y.

66 = 110(k); k = 0.6 (use this in the next part)

y = 80(.6) y = 48

I hope you understand the relationship between x and y when they vary directly.