You distribute whats outside the parentheses to whats inside. (Second line) Then, you add like terms, which is on one side, -15+2 is -13(third line). Then you single out the variable keeping it on one side by ,simply, subtracting 3x from 15x which is 12x(fourth line). Then you subtract 10 from -13 which is doing the opposite to get the variable by itself, that equals to -23. And, if you can have a decimal, then it comes to -23/12
Explanation: Area of a triangle= 1/2base x height Plug in information 30=1/2 x 4 x h Solve 1/2 x 4 = 2 30= 2 x h Divide both side by two 30/2=2 x h/2 Solve: 15= h
