Compare a and b with greater or less signs, if: 50% of a is equal to $0.5a and 20% of b is equal to $0.2a

4+6x-3x^3 in standard form with explanations because i don’t understand

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. what distance from city a is the point where the truck and the car will meet?