In a partnership business the monthly investment by three friends for the first six months is in the ratio 3 : 4 : 5. After six months, they had to increase their monthly investments by 10%, 15% and 20%, respectively, of then initial monthly investment. The new investment ratio was kept constant for the next six months.

What is the ratio of their shares in the total profit (m the same order) at the end of the year such that the share is proportional to their individual total investment over the year?

A survey of 450 students about their subjects of interest resulted in the following outcome.

$$\bullet$$ 150 students are interested in Mathematics.

$$\bullet$$ 200 students are interested in Physics.

$$\bullet$$ 175 students are interested in Chemistry.

$$\bullet$$ 50 students are interested in Mathematics and Physics.

$$\bullet$$ 60 students are interested in Physics and Chemistry.

$$\bullet$$ 40 students are interested in Mathematics and Chemistry.

$$\bullet$$ 30 students are interested in Mathematics, Physics and Chemistry.

$$\bullet$$ Remaining students are interested in Humanities.

Based on the above information, the number of students interested in Humanities is

$$x:y:z = {1 \over 2}:{1 \over 3}:{1 \over 4}$$

What is the value of $${{x + z - y} \over y}$$ = ?

Both the numerator and the denominator of $${3 \over 4}$$ are increased by a positive $${15 \over 17}$$ integer, x, and those of _____ are decreased by the same integer. This operation results in the same value for both the fractions. What is the value of x?