The price per pen is $ 0.31
The cost of 100 pens is $31
Solution:
Given that, Pens were on sale 4 for $1.24
Which means, 4 pens are sold are $ 1.24
Then cost of 1 pen is found by dividing 1.24 by 4


Thus one pen costs $ 0.31
B. how much would 100 pens cost?
The cost of 100 pens is found by multiplying 0.31 by 100


Thus cost of 100 pens is $ 31