How many solutions does each equation have

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. how many hours after the truck's departure will the two meet?

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Calculate the missing value. round the answer to on decimal place. start with 70, increase it by 21%, and end up with