Ответ:\(2.4\cdot7.4-1.7\cdot5.6-4.3\cdot3.1+5.3\cdot2.8=17.76-9.52-13.33+14.84=9.75\).\(-12.42:4.6-31.93:3.1+1.98:2.64+8.2\cdot0.4=-2.7-10.3+0.75+3.28=-8.97\).Ответ: а) 9,75; б) −8,97.