Answer:
a) Lenox will iron
of the shirts each day after school
.
b) If Lenox has 40 shirts, he will iron 12 shirts on Thursday and Friday.
Explanation:
a) Lenox has ironed
of the shirts over the weekend, so it means
will be split during the week (will be divided by 5):
Fraction of the shirts that will be ironed over the week:

Fraction of the shirts that will be ironed each day:

b) If Lenox has 40 shirts, it means that one-fourth is ironed over the weekend:

The rest of shirts is split in 5 days:

To sum up, if we multiply the calculated fraction in the previous question we can obtain the amount of shirts ironed each day:

As Thursday and Friday are two days, we have to multiply by 2 the previous result.
In conclusion, Lenox will iron 12 shirts on Thursday and Friday.