Carrie can do 2*45=<<2*45=90>>90 sit-ups per minute.
Jerrie can do 90+5=<<90+5=95>>95 sit-ups per minute.
In two minutes, Carrie would perform 90*2-180 sit-ups.
And in three minutes, Jerrie would perform 3 * 95=<<3*95=285>>285 sit-ups.
Thus, in the scenario described, in total, the three would perform 45+180+285=<<45+180+285=510>>510 sit-ups.
#### 510