Question

Sundar used linear combination to solve the system of equations shown. He did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. What number did Sundar multiply the second equation by?

Answer 1

Sundar intends to eliminate the y term, he has multiplied the first equation by 5, that makes the y term equal to 45y. He must now must select a number to make the y term in the second equation equal to 45y when multiplication is done. This number will be positive if Sundar intends to subtract, or negative if he intends to add.