1. a box of 80 coins, consisting of only nickels and dimes, is worth 7 dollars and 80 cents. find the number of nickels.
2. two drivers are 420 miles away from each other when they started moving towards each other. they meet after 4 hours. what is the speed of the first car, if the second car's speed is 45 mph?

Step-by-step explanation:

1. If all were dimes, the value would be $8.00. The value is actually $0.20 less than that. Replacing a dime by a nickel decreases the value by $0.05, so there must be $0.20/$0.05 = 4 nickels.

2. The total of the two speeds is the rate of closure: (420 mi)/(4 h) = 105 mi/h. The speed of the second car is found by subtracting the speed of the first car from this total:

  105 mph - 45 mph = 60 mph

no

step-by-step explanation:

2-7=-5

7-2=5

when you combing like terms for ech expression, 5 and -5. these numbers are not equal to each other.

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,