Michi put $7.50 worth of gas in her car. Two co-workers who were riding to work with her offered to share the cost of the gas. One paid 1/2 of the total amount and the other paid 1/3 of the total amount. How much of the total amount was left for Michi to pay?
One co-worker paid 1/2 of the $7.50 so they paid 1/2*$7.50 = $<<1/2*7.50=3.75>>3.75
One co-worker paid 1/3 of the $7.50 so they paid 1/3*$7.50 = $<<1/3*7.50=2.50>>2.50
The total amount paid by both co-workers is $3.75+$2.50 = $<<3.75+2.50=6.25>>6.25
Michi paid $7.50 - $6.25 = $<<7.50-6.25=1.25>>1.25. Answer: \boxed{1.25}.