You are right, didn't notice 47 3/4.I think there's enough information, but we need to be told a few things:
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Apart from the slanted line you're asking about, are all other angles right angles, and all lines that look sort of parallel, parallel?
If so, then it looks like you can draw in a right triangle like this, and calculate the vertical side a and the angle \(\theta\):
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Then it's just a little trig to find the horizontal side and the hypotenuse.