How many variables are in 10−3x+4y−z?

Astudent simplified a rational expression as shown.

Hillel is juggling flaming torches to raise money for charity. his initial appearance raises $500\$500 $500 , and he raises $15\$15 $15 for each minute of juggling performance. the amount rr r of money hillel raises is a function of tt t , the length of his performance in minutes. write the function's formula.

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?