3*(к+2 целых три пятых)=14
3(k+2.6)=14 3k+7.8=14 3k=14-7.8 3k=6.2 k=2.06
3*(k+2 3/5)=14 k+2 3/5=4 2/3 k=4 2/3-2 3/5 k=4 10/15-2 9/15 k=2 1/15