The sum of a number times 3 and 6 equals 4

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Astock has a 25% probability of increasing by $10 and a 75% probability of decreasing by $5. what is the stocks expected increase or decrease?