(a^2-b^2)/(c-a) - найти, еслиa/3=b/2=c/5  и 5a +b -2c = 28

[latex] \frac{a^2-b^2}{c-a}=\frac{(a-b)(a+b)}{c-a}\\\\ \frac{a}{3}=\frac{b}{2}=\frac{c}{5}\\\\ 5a+b-2c=28\\\\ 5a+\frac{2a}{3}-\frac{10a}{3}=28\\\\ 15a+2a-10a=28*3\\\\ a=12\\\\ b=2c-32\\\\ \frac{2c-32}{2}=\frac{c}{5}\\\\ c=20\\\\ b=8\\\\ \frac{a^2-b^2}{c-a}=\frac{80}{8}=10 [/latex]