Answer:
110 test
Step-by-step explanation:
Let
x ----> the number of packet of 10 test
y ----> the total cost
we know that
The number of packet of 10 test purchase multiplied by $11 plus the enrollment fee of $30 must be equal to $151
so
The linear equation that represent this scenario is
we have
substitute
Solve for x
subtract 30 both sides
Divide by 11 both sides
The number of packets purchase was 11
To find out the number of test, multiply the number of packets by 10