Question

Multiple Choice Evaluate the expression $x-y\text{when}x=12.8\text{and}y=4$.

$\begin{array}{l}F.3.2\\ G.8.8\\ H.12.4\\ I.13.2\end{array}$

Short answer

The value of the expression is $G. 8.8$.

Step-by-step solution

Step-1 – Apply the concept of addition and subtraction

Two numbers with similar signs get added and the resulting number carries the similar sign.

Two numbers with opposite signs get subtracted and the resulting number carries the sign of the larger number.

Step-2 – Apply the concept for addition and subtraction of decimals

To add or subtract two decimal numbers, write the numbers vertical with decimal point aligned vertically.

For example: to add the numbers 2.3 and 4.62, write these numbers vertically and add as shown below

$\begin{array}{l}2.3\\ \underset{¯}{+4.62}\\ 6.92\end{array}$

Step-3 – Evaluate the difference

To evaluate the expression $x-y$, substitute the values of x as 12.8 and y as 4 and then write the numbers vertically with aligned decimal and subtract them as shown below

$\begin{array}{l}12.8\\ \underset{¯}{-4.0}\\ 8.8\end{array}$

Thus, the value of the expression is $8.8$.

Hence, option (G.) is correct.