A decrease in the price of toothpaste in a tube can lead to a decrease in the purchase of toothpaste in a pump. This means: A. Toothpaste in a tube and in a pump are substitute goods and the demand curve for toothpaste in a tube will shift right. B. Toothpaste in a tube and in a pump are complementary goods and the demand curve for toothpaste in a tube will shift right. C. Toothpaste in a tube and in a pump are substitute goods and the demand curve for toothpaste in a pump will shift left. D. Toothpaste in a tube and in a pump are complementary goods and the demand curve for toothpaste in a pump will shift left. E. Toothpaste in a tube and in a pump are complementary goods and the demand curve for both toothpastes will shift left.

C. Toothpaste in a tube and in a pump are substitute goods and the demand curve for toothpaste in a pump will shift left.

Explanation:

toothpaste in a tube and toothpaste in a pump are substitute goods.

Substitute goods are goods that can be used in place of another good.

If the price of a good increases, the demand for the substitute increases and if the price of the good reduces, the demand for the substitute increases.

Only changes in price of a good can lead to movement along the demand curve for that good. A decrease in the price of  toothpaste in a tube would lead to a movement downward along the demand curve

Other factors affecting demand leads to a shift of the demand curve either to the right or to the left.

A decrease in the price of toothpaste in a tube would lead to a decrease in the purchase of toothpaste in a pump. This would lead to a leftward shift of the demand curve of toothpaste in a pump to the left.

answer; organizational;

u = 30

continuing your method

= +

subtract from both sides

= - thus

= -

= ⇒ u = 30