Ijust need understanding it so i can do the next one

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.