1) 787 * x - 7.286 = 20.259
2) 24.000 : (x - 12)= 80

787*х-7286=20259
787*х=20259+7286
787*х=27545
х=27545:787
х=35
__________
787*35-7286=20259

1)787*x-7.286=20.259
787*x=20.259+7.286
787*x=27.545
x=27.545/787
x=35
2)24.000/(x-12)=80
24.000=80*(x-12)
24.000=80*x-960
80*x=24.000+960
80*x=24.960
x=24.960/80
x=312