Question

ПОМОГИТЕ СРОЧНО АЛГЕБРА 7 КЛАСС ​

Answer 1

$1)\\4x-5y=4\cdot(-1,5)+5\cdot 0,3=-6+1,5=4,5\\\\2)\\2(3x-6)+4(7-5x)=6x-12+28-20x=-14x+16\\\\3)\\-1,2(2,5a-2\frac{1}{3}b)-\frac{3}{8}(-3\frac{1}{5}b+1,04a)=-3a+\frac{12}{10}\cdot \frac{7}{3}b)-\frac{3}{8}(-\frac{16}{5}b+\frac{104}{100}a)=\\\\-3a+\frac{14}{5}b+\frac{3}{8}\cdot \frac{16}{5}b-\frac{3}{8}\frac{26}{25}a=-3a+\frac{14}{5}b+\frac{6}{5}b-\frac{39}{100}a=-\frac{339}{100}a+4b\\\\-\frac{339}{100}\cdot\frac{2}{3}+4\cdot (-0,78)=\frac{113}{50}-3,12=2,26-3.12=-0,86$