How to solve system of equation by elimination

For f(x) = 3x+1 and g(x) = x2 - 6, find (g/f)(x)

Savannah had 40 iris blooms last year this year she had 15% more iris blooms how many more hours blooms did savannah have this year

The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales?