The value of m is 12 6/7.
Explanation:
To find m, we want one m instead of 7, so we divide both sides by 7. 7m/7 = 90/7, which would be m = 12 6/7.
It seems to me, that if you were to add the price of all three items together, then multiply by 7.5%, you'd have the answer. Remember that 7.5% = .075 ... in other words, that is the number you would multiply the sum of the items by. Does that help?
It was stated in the problem that a given volume of a is inversely proportional with the pressure of the system. It means that the as the volume increases, the pressure would decrease and as the volume decreases, the pressure would increase. We would express it as:
V α 1/P
To change it to an equality, we introduce a proportionality constant, k. We do as follows:
V = k/P
So, to determine what is asked, we need to first calculate for the value of k.
V = k/P
At V = 160 m^3 P = 108 cmHg
160 = k / (108)
k = 17280
Thus, at P = 87 cmHg
V = 17280 / 87
V = 198.62 m^3