Which is the first error that Tomas made? Tomas substituted the 3 for x when he should have substituted 6 for x. Tomas added 6 to both sides of the equation instead of subtracting 6. Tomas should have written the equation as . Tomas substituted 3 for x when he should have substituted 3 for y.

Step-by-step explanation:

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Given the equation 2x+6y=12 to represent the total cost, where x represents the number of pounds of granola and y represents the number of pounds of walnuts.

If he buys 3pounds of granola, and he need to get amount of walnut, he should have substituted x = 3 into the expression to get y as shown:

Comparing the calculation with Tomas's, we can see that Tomas added 6 to both sides of the equation on line 3 instead of subtracting 6 from both sides of the equation. This was Tomas first error.

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4

the answer is 489

step-by-step explanation: