We need to establish a formula where the costs of both accounts are equal.
For account 1, we have a fixed cost of 10 and a variable cost of .10 we would write the cost formula as .1x+10
For account 2, we have a fixed cost of 12 and a variable cost of .05, we write this formula as 12 + .05x
Set the two formulas equal to each other
.1x+10 = 12+ .05x
Solve for X
.05x= 2
x= 40
Someone would need to write 40 checks to make the two checking accounts equal.