Question

[(4x + 15) / 5x)] = 1/2

Answer 1

One way in which to approach this problem would be to treat it as an equation of ratios and to cross multiply:

[(4x + 15) / 5x)] = 1/2  could be written as:

4x + 15        1
----------- =  ---
     5x           2

Then 8x + 30 = 5x

3x = -30,  and so     x = -10 (answer).  Be certain to check this answer through substitution!