If a + b + c = -2 and x + y = 10,
what is -9a + 2x - 9b - 9c + 2y?

38
because since all abc and xy have the same coefficients it makes it easier. 
i just made a=-2, b=-4,and c=4 because when added up it equals -2
i also made both x and y =5 becasue when added up it equals 10
so, -9(-2)+2(5)-9(-4)-9(4)+2(5)
18+10+36-36+10=38

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post