My sister needs help with job advice!!?

Okay so my sister just got hired for this job and it pays about $7.50 an hr..but a temp agency just notified her and said that theres a job that pays $10 an hr but it only gonna last until Sept..She has to send in a resume and if there interested theyll call her for an interview..The 7.50 job is strict so she wont be able to take off days..idk what should she do?? I think she should take the $10 job but theres no guarntee she'll get it..HELP!!