Question 249975
Inequality are solved in a manner just like equalities. You use arithmetic operations (addition, subtraction, multiplication and division) to get the unknown (in this "x")on one side of the inequality and the terms without an unknown on the other side of the inequality.

So,

0.9x+3 < 1.7x-4

Subtract 0.9x from each side of the inequality.  

The inequality then reads  3 < 0.8x-4

Add 4 to each side of the inequality.

The inequality then reads 7 < .8x

Divide each side of the inequality by .8

The inequality then reads 7/.8 < x.

Then 70/8 < x