0.1x plus 0.9y equals -7.4 0.8x-0.4y equals 9.2?

Answer 1

0.1x + 0.9y = -7.4

multiply throughout by 8: 0.8x + 7.2y = -59.2

Subtract second equation from this: 7.6y = -68.4 so that y = -9

Substitute this value of y in the first equation: 0.1x - 8.1 = -7.4

so that 0.1x = 0.7 or x = 7

Solution: (x,y) = (7,-9)