Acylindrical specimen of a brass alloy having a length of 92 mm (3.622 in.) must elongate only 4.60 mm (0.1811 in.) when a tensile load of 93000 n (20910 lbf) is applied. under these circumstances what must be the radius of the specimen? consider this brass alloy to have the stress-strain behavior shown in the animated figure 7.12.

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.