Tomas is making trail mix using granola and walnuts. He can spend a total of $12 on the ingredients. He buys 3 0pounds of granola that costs $2.00 per pound. The walnuts cost $6 per pound. He uses 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. He solves the equation for y, the number of pounds of walnuts he can buy. 2x+6y=12 2(3)+6y=12 6+6y+6=12+6 6y=18 y=3 which is the first error that was made?