How do I do Distance Formula? Here is the equation ( or equations I don't know if it is a equation or 2 different ones) that I need help with They are late and I need to turn them in

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?

Solve the following simultaneous equation by using an algebraic method (either substitution or elimination) 2x + 3y=-4 4x-y=11

15m is what percent of 60m; 3m; 30m; 1.5 km? the last one is km not m