2/7 ( 1,4 а- 3 1/2 в) - 1.2 (5/6 а - 0,5 в) - упростить

$\frac{2}{7}*(1,4a-3\frac{1}{2}b)-1,2*(\frac{5}{6}a-0,5b)$ = $\frac{2}{7}*(1,4a-\frac{7}{2}b)-1,2*(\frac{5}{6}a-0,5b)$ = $\frac{2}{7}*1,4a-\frac{7}{2}b*\frac{2}{7}-1,2*(\frac{5}{6}a-0,5b)$ = $0,4a-b-1,2*(\frac{5}{6}a-0,5b)$ = $0,4a-b-1,2*\frac{5}{6}a-0,5b*(-1,2)$ = $0,4a-b-a-0,5b*(-1,2)$ = $0,4a-b-a+0,6b$ = $0,4a-a-b+0,6b$ = $-0,6a-0,4b$