4(x+7)=8x-20
4x+28=8x-20
28=4x-20
48=4x
x=12
The right answer is C. never
The quotient of two algebraic expressions is a<em> fractional expression.
</em> Moreover, the quotient of two <em>polynomials</em> such as:

is called a rational expression. So according to this definition rational expressions does not contain logarithmic functions. In fact, a rational expression is an expression that is the ratio of two polynomials like this:


As you've got 15%, the best thing to do is to find 10%, then multiply it by 1.5. Once you've found the tip, you add this onto the cost of the meal.
Therefore, the total cost of $25 meal with a 15% tip is $28.75
Hope this helps :)