The sum of two numbers is 11, and their difference is 9. what are the two numbers?

  10 and 1

Step-by-step explanation:

Let x and y represent the two numbers. The problem statement lets us write two equations describing their relationships:

  x + y = 11

  x - y = 9

Adding these equations together, we have ...

  (x +y) +(x -y) = (11) +(9)

  2x = 20

  x = 10 . . . . . . . . . you will notice this is the average of the two given numbers

Then ...

  10 + y = 11 . . . . substitute for x in the first equation

  y = 1 . . . . . . . subtract 10

The two numbers are 10 and 1.

3.4 pizzas

step-by-step explanation:

given is a scatter plot showing number of pizzas sold during weeks for different issues of coupon

y represents number of pizzas sold and x number of coupons issued

y is marked verticaly and x horizontally

the trend line is given as

y =3.4x+43

this says that even when no coupon is issued pizzas sold will be 43

and rate of change of pizza sold for 1 unit of coupon = slope = 3.4

i.e. when x increases by 1 unit y increases by 3.4 units

hence for each additional coupon issued 3.4 pizzas more will be sold

step-by-step :