Answer:
The answer is 1/9 and 1/2
D. Because you're multiplying 3 by a number which is what the variable represents (n), then you're just adding 7 to that which equals 19 all together. It all translates to 3n+7=19.
The equation that would best describe the situation would be the first option. To solve this question, simply break down the question into sections and then use variables X and y to represent each of the things asked for in the problem. We know the following:
X = no of tetra fish
Y = no of goldfish
If there is twice as much goldfish than tetra fish, then it would be 2y.
X = 2Y.
Then knowing what X and y represent, find the equation that gives the total cost of fish he bought, knowing that 1.50 is for a goldfish and 2.00 is for a tetra fish.