Please help Explanation will be appreciated thanks,

A; 6.3%

Step-by-step explanation:

Problem 1

For the first problem, we first want to find y so that we can plug it into the expression.

We can use elimination method for the system of equations to solve.

3x+3y=21

3x-y=5

We subtract both equations to eliminate x.

4y=16                                        [divide both sides by 4]

y=4

Now that we know y, we can plug it into the expression.

                                        [divide]

                                        [subtract]

We know that the answer is A.

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Problem 2

For the second problem, we need to know how to calculate percent error. The formula for precent error is . We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.

                              [subtract]

                                  [solve absolue value]

                                    [divide]

                              [multiply]

Since the problem said to round to one decimal place, we know that the answer is 6.3%.

17 1/3

step-by-step explanation: