I sold 210 subscriptions. The total is 6150 dollars. One year subscription is 23 dollars and a two year subscription is 45 dollars. How many of each did I sell?

Solution:

Let "a" be the number of one year subscription

Let "b" be the number of two year subscription

Cost of each one year subscription = $ 23

Cost of each two year subscription = $ 45

I sold 210 subscriptions

Therefore,

a + b = 210

b = 210 - a -------- eqn 1

The total is 6150 dollars

Therefore,

number of one year subscription x Cost of each one year subscription + number of two year subscription x Cost of each two year subscription = 6150

23a + 45b = 6150 -------- eqn 2

Substitute eqn 1 in eqn 2

23a + 45(210 - a) = 6150

23a + 9450 - 45a = 6150

22a = 3300

a = 150

Substitute a = 150 in eqn 1

b = 210 - 150

b = 60

Thus 150 one year subscription and 60 two year subscription were sold

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis:

okay..i will pick 8!