Use the GCF to write an equivalent expression in factored form for the expression 21a + 28y

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

Julie was able to walk 16 km through the zoo in 6 hours. how long will it take her to walk 24 km through the zoo?

If each bricks costs and he can only buy one brick how much will it cost him to get the material to put around the outside of his garden?