"950 feet in 19 minutes" can be expressed as the rate (950/19) (ft/min), and is negative because the diver is descending (going downward).
Simplifying, -950/19 (ft/min) = -50 (ft/min)
There are

ways of pairing up any 2 members from the pool of
contestants. Note that

so that

X can be 3 because:
(3+1)(3)=(4)(3)=12
I believe that is the only possible value for x.
Good luck to you!
Glass and Titanium. Glass is because (10,40) (y over x) is 4 and Titanium is because (10,60) is 6 cork and lead are not since when dividing y over x it doesn't equal 2.