You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

[EX Q]: Question: A broker invested her own money in the stock market. During the first year, she increased her stock market wealth by 40 percent. In the second year, largely as a result of a slump in the stock market, she suffered a 30 percent decrease in the value of her stock investments. What was the net increase or decrease on her overall stock investment wealth by the end of the second year?

Option A: 5%

Option B: 2%

Option C: 15%

Option D: 20%

Option E: 80%
[EX A]: Option B

[EX Q]: Question: A certain electric-company plan offers customers reduced rates for electricity used between 8 p.m. and 8 a.m. weekdays and 24 hours a day Saturdays and Sundays. Under this plan, the reduced rates Z apply to what fraction of a week?

Option A: 1/2

Option B: 5/8

Option C: 9/14

Option D: 16/21

Option E: 9/10
[EX A]: Option C

[EX Q]: Question: If the sides of a triangle are 30 cm, 40 cm and 50 cm, what is its area?

Option A: 400

Option B: 500

Option C: 550

Option D: 600

Option E: 700
[EX A]:
Option D