Data Sufficiency

Guy's net income equals his gross income minus his deductions. By what percent did Guy's net income change on January 1, 1989, when both his gross income and his deductions increased?

(1) Guy's gross income increased by 4 percent on January 1, 1989.
(2) Guy's deductions increased by 15 percent on January 1, 1989.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
[spoiler]




Net Income = N
Gross incode = G
deduction = D

n = g - d

COMBINING BOTH Option1. and Option2.

after the incerase of gross income and deductions
new net income = 1.04g - 1.15d

so the increase in gross = new net income - old net income
= .04g - .15d

so percent change ( increase) of net income = (.04g - .15d / g - d )* 100


Hence E[/spoiler]