60% of customers pay for their meals with a credit card. What fraction of customers did not use credit cards?

40% = 4/10  = 2/5

We can easily see that 60% +40% =100

But in calculi we could always show

x=10

6x + 4x =10x

10x - 4x = 6x

10x -6x =4x

When we add them together

we find 20

20/4 = square of 4 + 4/5

20 + 4 /2 x 3  = square of 6

x(x - 4) = x^2 - 4x

and we see the customers use credit above, where concerned the customers don't use credit we can show

x(x - 6)  

x^2 -6x

10^2 - 6x

100 - 60

=40

=4/10

=2/5

Step-by-step explanation:

x= 149. 24+7=31. 180-31=149

your welcome