If this is an equilateral triangle, we need half of it to find the height which is a leg of a right triangle with a hypotenuse of 15. That means that the base of this half triangle is 7.5. Use Pythagorean's Theorem to fine the height.

. x = 12.99 or 13
Your equation should look like this:
d = day
15 + 3.50d
Hope this helps!
You would need to take 500 * .52 = 260 next take 260 * .25 to find how many cats like fish which equals 65, the probability that it likes fish and it sleeps inside can be found by taking .52 * .25 = .13 so there would be a 13% chance of picking a cat that sleeps indoors and likes fish, 435 cats dont like fish found by taking 500-65=435 and finally to find how many cats sleep outside take 500-260=240 then take 240 * .625 = 150 then 240-150 = 90 so 90 cats like to sleep outside and like fish thats it!=) Hope this helps!