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
Answer:
Step-by-step explanation:
Each purchase will be the sum of products of item price and number of items. The two purchases give rise to two equations.
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<h3>equations</h3>The variables are defined in the problem statement. The two purchases are ...
11r +16m = 6.23
13r +7m = 6.41
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<h3>solution</h3>A calculator offers a simple way to find the solutions to these equations. The attachments show the solution to be ...
The cost of ribbon is $0.45; the cost of a marker is $0.08.
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The "cross-multiplication" method of solving these equations seems particularly useful when the coefficients are mutually prime. It starts with a rewrite to general form:
Then we define three "cross products":
Δ1 = (11)(7) -(13)(16) = -131
Δ2 = (16)(-6.41) -(7)(-623) = -58.95
Δ3 = (-6.23)(13) -(-6.41)(11) = -10.48
The solutions are ...
r = Δ2/Δ1 = -58.95/-131 = 0.45
m = Δ3/Δ1 = -10.48/-131 = 0.08
The cost of ribbon is $0.45; the cost of a marker is $0.08.
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For more about the cross-multiplication method you can read ...
