At a flower shop, 4 flowers cost $10. mrs. watson usually buys 12 flowers. during a sale, there is a 20% discount on every flower. how many flowers can mrs. watson buy during the sale if she spends the same amount of money that usually does?

Make a proportion to find the cost for 12 flowers based on the price for 4 flowers. 
4/10=12/x
Cross multiply and you get 4x=120 Divide 4 on both sides of the equation. 
X is $30.
Then, you find the unit price of 1 flower by dividing 10 by 4. Each flower cost $2.50. 
Convert 20% to decimal which is 0.2.
Multiply 0.2 by 2.5 and you get 0.5. Subtract 0.5 from 2.5 to get 2. 
Write an equation using the information: $2 for each flower and you only have $30 to spend. 
The equation is 2x=30. Divide 2 on both sides and you get x=15 flowers