Answer: 4 roses and 8 tulips.
Step-by-step explanation: Each rose costs $5, so she bought 4 of them, which is $20 so far. Since she already bought 4 roses, she bought twice that amount for tulips, which is 8. Each tulip costs $2, so that's $16. Add both $20 and $16 and you have $36.
Hope this helps! :)