Answer:
Something like 2x-50 [tex]\geq[/tex] $299
Step-by-step explanation:
Because when she doubles the number, that means it is multiplied by 2, but the number she has is unknown, so it's x. Then she takes $50, which means you have to subtract from the 2x. I put the [tex]\geq[/tex] because technically, the variable could be any number and you could still buy the $299 bike. But if you want an exact answer for the x would be $174.50. :)