Question

1) 9(7x-6)-18x
2) 7a-6(19-a)
3) 0.8(6x-2)+16(x-4)
4) 2.8(5b-6a)-(7b-8a)x1.2
5) -(-4.9-5.8c) - (3.1c-5.6)
6) 8/9( 2 1/4a-3/4b)-7/30( 4 2/7a-8 4/7b)

Answer 1

$\displaystyle\sf 1) 9(7x-6)-18x=63x-54-18x=45x-54\\\\ 2) 7a-6(19-a) =7a-114+6a=13a-114\\\\ 3) 0.8(6x-2)+16(x-4)=4,8x-1,6+16x-64=20,8x-65,6\\\\4) 2.8(5b-6a)-(7b-8a)\cdot1.2=14b-16,8a-8,4b+9,6a= 5,6b-7,2b\\\\ 5) -(-4.9-5.8c) - (3.1c-5.6)=4,9+5,8c-3,1c+5,6=2,7c+10,5\\\\ 6)\frac{8}{9}(2\frac{1}{4}a-\frac{3}{4}b)-\frac{7}{30}(4\frac{2}{7}a-8\frac{4}{7}b)=\frac{8}{9}* \frac{9a}{4}-\frac{8}{9}\cdot\frac{3b}{4}-\frac{7}{30}\cdot\frac{30a}{7}+\frac{7}{30}\cdot\frac{60b}{7}\\\\=2a-\frac{2}{3}b-a+2b=a+\frac{4}{3}b$