Solve the system of 2x-5y+z=1 3 y+2z=5-24z=48

Do you mind if you guys me with this question i’m on number 8

Can someone explain to me how to do

Abari owns 100 shares of stock a and 45 shares of stock b. for the past month, his stocks have been fluctuating inversely. stock a decreased by m cents per share and stock b increased by n cents per share. which equation can be used to find the total change in value of jabari's shares per month?