Solve 3x-y=-10 by substitution method

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1

:malik received a $300 gift card from his grandparents and is using it only to pay for his karate lessons, which cost $30 per month. determine what amount, in dollars, remains on the card after 8 months.

15. if the 8% tax on an item amounts to $0.96, what is the final price (tax included) of the item?