<span>At 8in to 250 feet the skyscraper converts to the following.
1.6 in/8 in x 250ft = 50 ft long
2.8in/8in x 250ft = 87.5 ft wide
11.2in/8in x 250ft = 350 ft high
You get this because every 8 in is 250 feet so you need to calculate the ratio of scale to that 8in per 250 feet.</span>
If 3c+4d=2 then c=(2-4d)/3
And if you put that into the other equation

Then you multiply everything by 3, getting

And then

Leaving

I dont have a calc with me right now but you just pot this into the calculator:

And when you get the number you insert it into the nest eqation to get c

So basically
1.84 * 10^-6
Hope this helpsss