3x + y = -1
2x + 3y = 18

Step-by-step explanation:

Multiply by -3 the upper equation to make y equal in value but with opposite signs.

Now add equation 1 and 2.

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Solve for x;

To isolate x, divide by -7

Now use one of the equations above and replace the value of x.

To prove if it's correct, take either equation and replace both x and y values, if the results are equal to each other, it is correct.

6 hours 48 min

step-by-step explanation:

68÷5=13.6

13.6×30=408min=6 hours 48 min.

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