Turn the algebra into English.
Define your variable.
Let x = your figure
Note that to find a percentage of a number, you must convert your percent to a decimal and then multiply. To convert a percentage to a decimal, divide it by 100 (move the decimal two places to the left).
Your calculation is
(x - 0.075x) - (0.19)(x - 0.075x)
= (0.74925)x