Let x=the amount of roses that Brad buys. (x+3)=the number of daisies that Brad buys.
x+(x+3)=33
Simplify this problem to find the amount of roses:
2x+3=33
2x=30
x=15
So, Brad buys 15 roses and 18 daisies.
Since roses cost $3, 15*3=45.
The roses cost $45.
Hope this helps! :)