小白求大神相助，解三元三次方程~~！！！

(1) 99*(b+c)+[75-(b+c)]*a=4913.23
(2) 99*b*[75-b/2]+99*c*c/2+a*(75-b-c)*[(75-b-c)/2]=37.07
(3) 1/12*99*b^3+99*b*[75-37.07-(b/2)]^2+1/12*99*c^2+99*c*[37.07-(c/2)]^2+1/12a*(75-b-c)^3+a(75-b-c)*[(75-b-c)/2-37.07]^2=4914,23