SATMathematics Practice Test 1

The description “$16+4\mathit{x}$ is 10 more than 14” can be written as the equation $16+4\mathit{x}=10+14$, which is equivalent to $16+4\mathit{x}=24$.
Subtracting 16 from each side of $16+4\mathit{x}=24$ gives $4\mathit{x}=8$. Since $8\mathit{x}$ is 2 times 4x, multiplying both sides of $4\mathit{x}=8$ by 2 gives $8\mathit{x}=16$.
Therefore, the value of $8\mathit{x}$ is 16.
Choice A is incorrect because it is the value of x, not 8x.
Choices B and D are incorrect; those choices may be a result of errors in rewriting $16+4\mathit{x}=10+14$.
For example, choice D could be the result of subtracting 16 from the left side of the equation and adding 16 to the right side of $16+4\mathit{x}=10+14$, giving $4\mathit{x}=40$ and $8\mathit{x}=80$