When you go up it’s positive and when you do down it’s negative. Hope this helps. Mark as brainliest please
![\rho = \frac{m}{V} \Rightarrow V=\frac{m}{\rho}](https://tex.z-dn.net/?f=%5Crho%20%3D%20%5Cfrac%7Bm%7D%7BV%7D%20%5CRightarrow%20V%3D%5Cfrac%7Bm%7D%7B%5Crho%7D)
ρ - density, m - mass, V - volume
Liquid A:
![\rho=0.7 \ \frac{g}{cm^3} \\ m=140 \ g \\ \\ V=\frac{140 \ g}{0.7 \ \frac{g}{cm^3}}=200 \ cm^3](https://tex.z-dn.net/?f=%5Crho%3D0.7%20%5C%20%5Cfrac%7Bg%7D%7Bcm%5E3%7D%20%5C%5C%0Am%3D140%20%5C%20g%20%5C%5C%0A%5C%5C%20V%3D%5Cfrac%7B140%20%5C%20g%7D%7B0.7%20%5C%20%5Cfrac%7Bg%7D%7Bcm%5E3%7D%7D%3D200%20%5C%20cm%5E3)
Liquid B:
![\rho=1.6 \ \frac{g}{cm^3} \\ m=128 \ g \\ \\ V=\frac{128 \ g}{1.6 \ \frac{g}{cm^3}}=80 \ cm^3](https://tex.z-dn.net/?f=%5Crho%3D1.6%20%5C%20%5Cfrac%7Bg%7D%7Bcm%5E3%7D%20%5C%5C%0Am%3D128%20%5C%20g%20%5C%5C%0A%5C%5C%20V%3D%5Cfrac%7B128%20%5C%20g%7D%7B1.6%20%5C%20%5Cfrac%7Bg%7D%7Bcm%5E3%7D%7D%3D80%20%5C%20cm%5E3)
Liquid C:
![m=140 \ g + 128 \ g=268 \ g \\ V=200 \ cm^3 + 80 \ cm^3=280 \ cm^3 \\ \\ \rho=\frac{268 \ g}{280 \ cm^3} \approx 0.96 \ \frac{g}{cm^3}](https://tex.z-dn.net/?f=m%3D140%20%5C%20g%20%2B%20128%20%5C%20g%3D268%20%5C%20g%20%5C%5C%0AV%3D200%20%5C%20cm%5E3%20%2B%2080%20%5C%20cm%5E3%3D280%20%5C%20cm%5E3%20%5C%5C%20%5C%5C%0A%5Crho%3D%5Cfrac%7B268%20%5C%20g%7D%7B280%20%5C%20cm%5E3%7D%20%5Capprox%200.96%20%5C%20%5Cfrac%7Bg%7D%7Bcm%5E3%7D)
The density of liquid C is approximately 0.96 g/cm³.
10/2.5=4
4*2/5 = 8/5 =1 3/5 or 1.6 pounds
It may be misleading because it only tells you those two years, not what happened between those years