A store is selling ribbon by the yard. Mike bought 8 yards of red ribbon. Each yard cost $3.50. Complete and solve working equation that represents the amount, a, Mike paid for buying 8 yards of ribbon

Let a represent the amount Mike paid for buying 8 yards of ribbon.

Since each yard of ribbon costs $3.50, the equation can be written as:
a = 8 * 3.50
Now, we can solve for a by multiplying:
a = 28.00
Therefore, Mike paid $28.00 for buying 8 yards of ribbon.