[tex] \frac{a}{n} = \frac{b}{m} = \frac{c}{p} = \frac{b}{q} = \frac{a + b + c + d}{n + m + p + q} = 7[/tex]
[tex] {7}^{2} - \frac{a + b + c + d}{n + m + p + q} = {7}^{2} - 7 = [/tex]
[tex] = 49 - 7 = 42[/tex]
[tex] \frac{a}{n} = \frac{b}{m} = \frac{a + b }{n + m } = 7[/tex]
[tex] \frac{b}{m} = \frac{c}{p} = \frac{b+c }{m + p} = 7[/tex]
[tex] \frac{c}{p} = \frac{d}{q} = \frac{c+ d }{p + q } = 7[/tex]
[tex] \frac{d}{q} = \frac{a}{n} = \frac{d + a}{q + n } = 7[/tex]
[tex] \frac{a + b }{n + m } + \frac{b + c}{m + p} + \frac{c + d}{p + q} + \frac{d + a}{q + n} - 17 = [/tex]
[tex] = 7 + 7 + 7 + 7 - 17 = [/tex]
[tex] = 28 - 17 = 11[/tex]
