Question

If $3x+4y$ is added to $7x-5y$, then find the coefficient of $y$ in the algebraic expression obtained by evaluating the sum.

• A. $4$
• B. $-5$
• C. $1$
• D. $-1$

Answer 1

The correct option is D $-1$

$\underset{–}{Step1:}$

First, we need to add $3x+4y$ and $7x-5y$.

The sum can be evaluated using Horizontal Method as:
$(3x+4y)+(7x-5y)$
Combining the like terms together:
$(3x+7x)+(4y-5y)$
Adding the like terms:
$\underset{–}{(3x+7x)}+\underset{–}{(4y-5y)}$
$=10x+(-1)y$
$=10x-y$

The sum can also be evalauted using Column Method as:



$\underset{–}{Step2:}$

The sum of $3x+4y$ and $7x-5y$ is $10x-y$.
$10x-y$ can be written as:
$10x-y=10x+(-1)y$

In $10x-y$,
Coefficient of $x$ is $10$.
Coefficient of $y$ is $-1$.

Therefore, option (d.) is the correct answer.